JP4500420B2 - Photoelectric conversion element and photovoltaic cell - Google Patents

Description

【００３２】
（ただし、R_aは水素原子または置換基を表し、置換基としてはたとえば、ハロゲン原子、炭素原子数１〜12の置換または無置換のアルキル基、炭素原子数７〜12の置換または無置換のアラルキル基、炭素原子数６〜12の置換または無置換のアリール基、あるいは前述の酸性基（これらの酸性基は塩を形成していてもよい）やキレート化基が挙げられ、アルキル基およびアラルキル基のアルキル部分は直鎖状でも分岐状でもよく、またアリール基およびアラルキル基のアリール部分は単環でも多環（縮合環、環集合）でもよい）により表される化合物から選ばれた有機配位子を表す。B-a、B-bおよびB-cは同一でも異なっていてもよく、いずれか１つまたは２つでもよい。
【００３３】
有機金属錯体色素の好ましい具体例を以下に示すが、本発明はこれらに限定されるものではない。
【００３４】
【化２】

【００３５】
【化３】

【００３６】
【化４】

【００３７】
（b）メチン色素
本発明に使用する色素の好ましいメチン色素は、シアニン色素、メロシアニン色素、スクワリリウム色素などのポリメチン色素である。本発明で好ましく用いられるポリメチン色素の例は、特開平１１−３５８３６号、特開平１１−６７２８５号、特開平１１−８６９１６号、特開平１１−９７７２５号、特開平１１−１５８３９５号、特開平１１−１６３３７８号、特開平１１−２１４７３０号、特開平１１−２１４７３１号、特開平１１−２３８９０５号、特開２０００−２６４８７号、欧州特許８９２４１１号、同９１１８４１号および同９９１０９２号の各明細書に記載の色素である。好ましいメチン色素の具体例を以下に示す。
【００３８】
【化５】

【００３９】
（４）半導体微粒子への色素の吸着
半導体微粒子に色素を吸着させるには、良く乾燥した半導体微粒子層を有する導電性支持体を色素の溶液中に浸漬するか、色素の溶液を半導体微粒子層に塗布する方法を用いることができる。前者の場合、浸漬法、ディップ法、ローラ法、エアーナイフ法等が使用可能である。浸漬法の場合、色素の吸着は室温で行ってもよいし、特開平7-249790号に記載されているように加熱還流して行ってもよい。また後者の塗布方法としては、ワイヤーバー法、スライドホッパー法、エクストルージョン法、カーテン法、スピン法、スプレー法等がある。色素を溶解する溶媒として好ましいのは、例えば、アルコール類（メタノール、エタノール、t-ブタノール、ベンジルアルコール等）、ニトリル類（アセトニトリル、プロピオニトリル、3-メトキシプロピオニトリル等）、ニトロメタン、ハロゲン化炭化水素（ジクロロメタン、ジクロロエタン、クロロホルム、クロロベンゼン等）、エーテル類（ジエチルエーテル、テトラヒドロフラン等）、ジメチルスルホキシド、アミド類（N,N-ジメチルホルムアミド、N,N-ジメチルアセタミド等）、N-メチルピロリドン、1,3-ジメチルイミダゾリジノン、3-メチルオキサゾリジノン、エステル類（酢酸エチル、酢酸ブチル等）、炭酸エステル類（炭酸ジエチル、炭酸エチレン、炭酸プロピレン等）、ケトン類（アセトン、2-ブタノン、シクロヘキサノン等）、炭化水素（へキサン、石油エーテル、ベンゼン、トルエン等）やこれらの混合溶媒が挙げられる。
【００４０】
色素の全吸着量は、多孔質半導体電極基板の単位表面積（１m²）当たり0.01〜100mmolが好ましい。また色素の半導体微粒子に対する吸着量は、半導体微粒子１g当たり0.01〜１mmolの範囲であるのが好ましい。このような色素の吸着量とすることにより半導体における増感効果が十分に得られる。これに対し、色素が少なすぎると増感効果が不十分となり、また色素が多すぎると半導体に付着していない色素が浮遊し、増感効果を低減させる原因となる。色素の吸着量を増大させるためには、吸着前に加熱処理を行うのが好ましい。加熱処理後、半導体微粒子表面に水が吸着するのを避けるため、常温に戻さずに、半導体電極基板の温度が60〜150℃の間で素早く色素の吸着操作を行うのが好ましい。また、色素間の凝集などの相互作用を低減する目的で、無色の化合物を色素に添加し、半導体微粒子に共吸着させてもよい。この目的で有効な化合物は界面活性な性質、構造をもった化合物であり、例えば、カルボキシル基を有するステロイド化合物（例えばケノデオキシコール酸）や下記の例のようなスルホン酸塩類が挙げられる。
【００４１】
【化６】

【００４２】
（C）電荷輸送層
電荷輸送層は、色素の酸化体に電子を補充する機能を有する電荷輸送材料を含有する層である。本発明で用いることのできる代表的な電荷輸送材料の例としては、(i)イオン輸送材料として、酸化還元対のイオンが溶解した溶液（電解液）、酸化還元対の溶液をポリマーマトリクスのゲルに含浸したいわゆるゲル電解質、酸化還元対イオンを含有する溶融塩電解質、さらには固体電解質が挙げられる。また、イオンがかかわる電荷輸送材料のほかに、(ii)固体中のキャリアー移動がかかわる電荷輸送材料として、電子輸送材料や正孔（ホール）輸送材料を用いることもできる。これらの電荷輸送材料は、併用することができる。
【００４３】
（１）溶融塩電解質
溶融塩電解質は、光電変換効率と耐久性の両立という観点から特に好ましい。溶融塩電解質とは、室温において液状であるか、または低融点の電解質であり、例えばWO95/18456号、特開平8-259543号、電気化学，第65巻，11号，923頁（1997年）等に記載されているピリジニウム塩、イミダゾリウム塩、トリアゾリウム塩等の既知の電解質を挙げることができる。１００℃以下、特に室温付近において液状となる溶融塩が好ましい。
【００４４】
好ましく用いることのできる溶融塩としては、下記一般式（Y-a）、（Y-b）及び（Y-c）のいずれかにより表されるものが挙げられる。
【００４５】
【化７】

【００４６】
一般式（Y-a）中、Q_y1は窒素原子と共に５又は６員環の芳香族カチオンを形成しうる原子団を表す。Q_y1は炭素原子、水素原子、窒素原子、酸素原子及び硫黄原子からなる群から選ばれる１種以上の原子により構成されるのが好ましい。Q_y1により形成される５員環は、オキサゾール環、チアゾール環、イミダゾール環、ピラゾール環、イソオキサゾール環、チアジアゾール環、オキサジアゾール環、トリアゾール環、インドール環またはピロール環であるのが好ましく、オキサゾール環、チアゾール環又はイミダゾール環であるのがより好ましく、オキサゾール環又はイミダゾール環であるのが特に好ましい。Q_y1により形成される６員環は、ピリジン環、ピリミジン環、ピリダジン環、ピラジン環又はトリアジン環であるのが好ましく、ピリジン環であるのがより好ましい。
【００４７】
一般式（Y-b）中、A_y1は窒素原子又はリン原子を表す。
【００４８】
一般式（Y-a）、（Y-b）及び（Y-c）中のR_y1〜R_y6はそれぞれ独立に置換又は無置換のアルキル基（好ましくは炭素原子数１〜24、直鎖状であっても分岐状であっても、また環式であってもよく、例えばメチル基、エチル基、プロピル基、イソプロピル基、ペンチル基、ヘキシル基、オクチル基、2-エチルヘキシル基、t-オクチル基、デシル基、ドデシル基、テトラデシル基、2-ヘキシルデシル基、オクタデシル基、シクロヘキシル基、シクロペンチル基等）、或いは置換又は無置換のアルケニル基（好ましくは炭素原子数２〜24、直鎖状であっても分岐状であってもよく、例えばビニル基、アリル基等）を表し、より好ましくは炭素原子数２〜18のアルキル基又は炭素原子数２〜18のアルケニル基であり、特に好ましくは炭素原子数２〜６のアルキル基である。
【００４９】
また、一般式（Y-b）中のR_y1〜R_y4のうち２つ以上が互いに連結してA_y1を含む非芳香族環を形成してもよく、一般式（Y-c）中のR_y1〜R_y6のうち２つ以上が互いに連結して環構造を形成してもよい。
一般式（Y-a）、（Y-b）及び（Y-c）中のQ_y1及びR_y1〜R_y6は置換基を有していてもよく、好ましい置換基の例としては、ハロゲン原子（F、Cl、Br、I等）、シアノ基、アルコキシ基（メトキシ基、エトキシ基、メトキシエトキシ基、メトキシエトキシエトキシ基等）、アリーロキシ基（フェノキシ基等）、アルキルチオ基（メチルチオ基、エチルチオ基等）、アルコキシカルボニル基（エトキシカルボニル基等）、炭酸エステル基（エトキシカルボニルオキシ基等）、アシル基（アセチル基、プロピオニル基、ベンゾイル基等）、スルホニル基（メタンスルホニル基、ベンゼンスルホニル基等）、アシルオキシ基（アセトキシ基、ベンゾイルオキシ基等）、スルホニルオキシ基（メタンスルホニルオキシ基、トルエンスルホニルオキシ基等）、ホスホニル基（ジエチルホスホニル基等）、アミド基（アセチルアミノ基、ベンゾイルアミノ基等）、カルバモイル基（N,N-ジメチルカルバモイル基等）、アルキル基（メチル基、エチル基、プロピル基、イソプロピル基、シクロプロピル基、ブチル基、2-カルボキシエチル基、ベンジル基等）、アリール基（フェニル基、トルイル基等）、複素環基（ピリジル基、イミダゾリル基、フラニル基等）、アルケニル基（ビニル基、1-プロペニル基等）、シリル基、シリルオキシ基等が挙げられる。
一般式（Y-a）、（Y-b）又は（Y-c）により表される化合物は、Q_y1又はR_y1〜R_y6を介して多量体を形成してもよい。
【００５０】
これらの溶融塩は、単独で使用しても、２種以上混合して使用してもよく、また、ヨウ素アニオンを他のアニオンで置き換えた溶融塩と併用することもできる。ヨウ素アニオンと置き換えるアニオンとしては、ハロゲン化物イオン（Cl^-、Br^-等）、SCN^-、BF₄ ^-、PF₆ ^-、ClO₄ ^-、(CF₃SO₂)₂N^-、(CF₃CF₂SO₂)₂N^-、CH₃SO₃ ^-、CF₃SO₃ ^-、CF₃COO^-、Ph₄B^-、(CF₃SO₂)₃C^-等が好ましい例として挙げられ、SCN^-、CF₃SO₃ ^-、CF₃COO^-、(CF₃SO₂)₂N^-又はBF₄ ^-であるのがより好ましい。また、LiIなど他のヨウ素塩やCF₃COOLi、CF₃COONa、LiSCN、NaSCNなどのアルカリ金属塩を添加することもできる。アルカリ金属塩の添加量は、0.02〜２質量％程度であるのが好ましく、0.1〜１質量％がさらに好ましい。
【００５１】
本発明で好ましく用いられる溶融塩の具体例を以下に挙げるが、これらに限定されるわけではない。
【００５２】
【化８】

【００５３】
【化９】

【００５４】
【化１０】

【００５５】
【化１１】

【００５６】
【化１２】

【００５７】
【化１３】

【００５８】
上記溶融塩電解質は常温で溶融状態であるものが好ましく、溶媒を用いない方が好ましい。後述する溶媒を添加しても構わないが、溶融塩の含有量は電解質組成物全体に対して50質量％以上であるのが好ましく、90質量％以上であるのが特に好ましい。また、塩のうち、50質量％以上がヨウ素塩であることが好ましい。
【００５９】
上記電解質組成物にはヨウ素を添加するのが好ましく、この場合、ヨウ素の含有量は、電解質組成物全体に対して0.1〜20質量％であるのが好ましく、0.5〜５質量％であるのがより好ましい。
【００６０】
（２）電解液
電荷輸送層に電解液を使用する場合、電解液は電解質、溶媒、および添加物から構成されることが好ましい。本発明の電解質はＩ₂とヨウ化物の組み合わせ（ヨウ化物としてはＬｉＩ、ＮａＩ、ＫＩ、ＣｓＩ、ＣａＩ₂ などの金属ヨウ化物、あるいはテトラアルキルアンモニウムヨーダイド、ピリジニウムヨーダイド、イミダゾリウムヨーダイドなど４級アンモニウム化合物のヨウ素塩など）、Ｂｒ₂と臭化物の組み合わせ（臭化物としてはＬｉＢｒ、ＮａＢｒ、ＫＢｒ、ＣｓＢｒ、ＣａＢｒ₂ などの金属臭化物、あるいはテトラアルキルアンモニウムブロマイド、ピリジニウムブロマイドなど４級アンモニウム化合物の臭素塩など）のほか、フェロシアン酸塩−フェリシアン酸塩やフェロセン−フェリシニウムイオンなどの金属錯体、ポリ硫化ナトリウム、アルキルチオール−アルキルジスルフィドなどのイオウ化合物、ビオロゲン色素、ヒドロキノン−キノンなどを用いることができる。この中でもI₂とＬｉＩやピリジニウムヨーダイド、イミダゾリウムヨーダイドなど４級アンモニウム化合物のヨウ素塩を組み合わせた電解質が好ましい。上述した電解質は混合して用いてもよい。
電解質の好ましい濃度は0.1M〜10Mであり、さらに好ましくは0.2M〜４Mである。また、電解液にヨウ素を添加する場合の好ましいヨウ素の添加濃度は0.01Mから0.5Mである。
【００６１】
電解質に使用する溶媒は、粘度が低くイオン易動度を向上したり、もしくは誘電率が高く有効キャリアー濃度を向上したりして、優れたイオン伝導性を発現できる化合物であることが望ましい。このような溶媒としては、エチレンカーボネート、プロピレンカーボネートなどのカーボネート化合物、３−メチル−２−オキサゾリジノンなどの複素環化合物、ジオキサン、ジエチルエーテルなどのエーテル化合物、エチレングリコールジアルキルエーテル、プロピレングリコールジアルキルエーテル、ポリエチレングリコールジアルキルエーテル、ポリプロピレングリコールジアルキルエーテルなどの鎖状エーテル類、メタノール、エタノール、エチレングリコールモノアルキルエーテル、プロピレングリコールモノアルキルエーテル、ポリエチレングリコールモノアルキルエーテル、ポリプロピレングリコールモノアルキルエーテルなどのアルコール類、エチレングリコール、プロピレングリコール、ポリエチレングリコール、ポリプロピレングリコール、グリセリンなどの多価アルコール類、アセトニトリル、グルタロジニトリル、メトキシアセトニトリル、プロピオニトリル、ベンゾニトリルなどのニトリル化合物、ジメチルスルフォキシド、スルフォランなど非プロトン性の極性物質、水などが挙げられ、これらを混合して用いることもできる。
【００６２】
また、本発明では、ジャーナル・オブ・アメリカン・セラミック・ソサエティー（ J. Am. Ceram. Soc .）,80巻 (12)号3157-3171頁(1997)に記載されているようなtert-ブチルピリジンや、２−ピコリン、２，６−ルチジン等の塩基性化合物を前述の溶融塩電解質や電解液に添加することが好ましい。塩基性化合物を添加する場合の好ましい濃度範囲は0.05M〜2Mである。
【００６３】
（３）ゲル電解質
本発明では、電解質はポリマー添加、オイルゲル化剤添加、多官能モノマー類を含む重合、ポリマーの架橋反応等の手法により、前述の溶融塩電解質や電解液をゲル化（固体化）させて使用することもできる。ポリマー添加によりゲル化させる場合は、“Polymer Electrolyte Revi ews-１および２”(マッカラン（J.R.MacCallum）とビンセント（C.A. Vincent）の共編、ELSEVIER APPLIED SCIENCE)に記載された化合物を使用することができるが、特にポリアクリロニトリル及びポリフッ化ビニリデンを好ましく使用することができる。オイルゲル化剤添加によりゲル化させる場合は，日本化学会刊、工業化学雑誌（J. Chem Soc. Japan, Ind. Chem.Sec.）, 46巻,779頁(1943),米国化学会誌（ J. Am. Chem. Soc.）, 111巻,5542頁(1989), J. Chem. Soc., Chem. Commun.,（1993）, 390頁, Angew. Chem. (英語版), 35巻,1949頁(1996), Chem. Lett., （1996）, 885頁, J. Chm. Soc., Chem. Commun., （1997）,545頁に記載されている化合物を使用することができるが、好ましい化合物は分子構造中にアミド構造を有する化合物である。電解液をゲル化した例は特開平１１−１８５８６３号公報に、溶融塩電解質をゲル化した例は特開２０００−５８１４０号公報に記載されており、本発明にも適用できる。
【００６４】
また、ポリマーの架橋反応により電解質をゲル化させる場合、架橋可能な反応性基を含有するポリマーおよび架橋剤を併用することが望ましい。この場合、好ましい架橋可能な反応性基は、アミノ基、含窒素複素環基（例えば、ピリジン環、イミダゾール環、チアゾール環、オキサゾール環、トリアゾール環、モルホリン環、ピペリジン環、ピペラジン環などを骨格とする環基）であり、好ましい架橋剤は、窒素原子に対して求電子反応可能な２官能以上の試薬（例えば、ハロゲン化アルキル類、ハロゲン化アラルキル類、スルホン酸エステル類、酸無水物、酸クロライド類、イソシアネート化合物、α、β−不飽和スルホニル基含有化合物、α、β−不飽和カルボニル基含有化合物、α、β−不飽和ニトリル基含有化合物など）であり、特開２０００−１７０７６号、同２０００−８６７２４号の各公報に記載されている架橋技術も適用できる。
【００６５】
（４）正孔輸送材料
本発明では、溶融塩などのイオン伝導性電解質の代わりに、有機または無機あるいはこの両者を組み合わせた固体の正孔輸送材料を使用することができる。
（a）有機正孔輸送材料
本発明に適用可能な有機正孔輸送材料としては、ハーゲン（J.Hagen）ほか,Synthetic Metal 89巻(1997)215-220頁、Nature,Vol.395巻, 8 Oct.号、（1998）,583-585頁およびWO97/10617号、特開昭59−194393号公報、特開平5−234681号公報、米国特許第4，923，774号、特開平4−308688号公報、米国特許第4，764，625号、特開平3−269084号公報、特開平4−129271号公報、特開平4−175395号公報、特開平4−264189号公報、特開平4−290851号公報、特開平4−364153号公報、特開平5−25473号公報、特開平5−239455号公報、特開平5−320634号公報、特開平6−1972号公報、特開平7-138562号、特開平7-252474号、特開平11-144773号の各公報に示される芳香族アミン類や、特開平11-149821号、特開平11-148067号、特開平11-176489号等の各公報に記載のトリフェニレン誘導体類を好ましく用いることができる。また、Adv. Mater. （1997）,9巻,N0.7,557頁、Angew. Chem.(英語版)、（1995）, 34巻, No.3,303-307頁、米国化学会誌（ J. Am. Chem. Soc.）, 1２０巻, N0.4,（1998）,664-672頁等に記載されているオリゴチオフェン化合物、K. Murakoshi おか,;Chem. Lett.（1997）,471頁に記載のポリピロール、“Handbook of Organic Conductive Molecules and Polymers 、1,2,3,4巻” （NALWA著、WILEY出版）に記載されているポリアセチレンおよびその誘導体、ポリ(p-フェニレン) およびその誘導体、ポリ( p-フェニレンビニレン) およびその誘導体、ポリチエニレンビニレンおよびその誘導体、ポリチオフェンおよびその誘導体、ポリアニリンおよびその誘導体、ポリトルイジンおよびその誘導体等の導電性高分子を好ましく使用することができる。
【００６６】
正孔（ホール）輸送材料にはNature,395巻, （１９９８、8 Oct.号）、583-585頁に記載されているようにドーパントの濃度レベルをコントロールするためにトリス（４-ブロモフェニル）アミニウムヘキサクロロアンチモネートのようなカチオンラジカルを含有する化合物を添加したり、酸化物半導体表面のポテンシャル制御（空間電荷層の補償）を行うためにLi[(CF_３SO_２)_２N]のような塩を添加しても構わない。
【００６７】
（b）無機正孔輸送材料
無機正孔輸送材料としては、ｐ型無機化合物半導体を用いることができる。この目的のｐ型無機化合物半導体は、バンドギャップが2eV以上であることが好ましく、さらに2.5eV以上であることが好ましい。また、ｐ型無機化合物半導体のイオン化ポテンシャルは色素の正孔を還元できる条件から、色素吸着電極のイオン化ポテンシャルより小さいことが必要である。使用する色素によってｐ型無機化合物半導体のイオン化ポテンシャルの好ましい範囲は異なってくるが、一般に4.5eV〜5.5eVであることが好ましく、さらに4.7eV〜5.3eVであることが好ましい。好ましいｐ型無機化合物半導体は一価の銅を含む化合物半導体であり、一価の銅を含む化合物半導体の例としてはCuI, CuSCN, CuInSe₂, Cu(In,Ga)Se₂, CuGaSe₂, Cu₂O, CuS, CuGaS₂, CuInS₂, CuAlSe₂などが挙げられる。この中でもCuIおよび CuSCNが好ましく、CuIが最も好ましい。このほかのｐ型無機化合物半導体として、GaP、NiO、CoO、FeO、Bi₂O₃、MoO₂、Cr₂O₃等を用いることができる。
【００６８】
（D）対極
対極は前記の導電性支持体と同様に、導電性材料からなる対極導電層の単層構造でもよいし、対極導電層と支持基板から構成されていてもよい。対極導電層に用いる導電材としては、金属（例えば白金、金、銀、銅、アルミニウム、マグネシウム、インジウム等）、炭素、または導電性金属酸化物（インジウム−スズ複合酸化物、フッ素ドープ酸化スズ、等）が挙げられる。この中でも白金、金、銀、銅、アルミニウム、マグネシウムを対極層として好ましく使用することができる。対極の好ましい支持基板の例は、ガラスまたはプラスチックであり、これに上記の導電剤を塗布または蒸着して用いる。対極導電層の厚さは特に制限されないが、３nm〜10μmが好ましい。対極層の表面抵抗は低い程よい。好ましい表面抵抗の範囲としては50Ω／□以下であり、さらに好ましくは20Ω／□以下である。
【００６９】
導電性支持体と対極のいずれか一方または両方から光を照射してよいので、感光層に光が到達するためには、導電性支持体と対極の少なくとも一方が実質的に透明であれば良い。発電効率の向上の観点からは、導電性支持体を透明にして、光を導電性支持体側から入射させるのが好ましい。この場合対極は光を反射する性質を有するのが好ましい。このような対極としては、金属または導電性の酸化物を蒸着したガラスまたはプラスチック、あるいは金属薄膜を使用できる。
【００７０】
対極は、電荷輸送層上に直接導電材を塗布、メッキまたは蒸着（PVD、CVD）するか、導電層を有する基板の導電層側を貼り付ければよい。また、導電性支持体の場合と同様に、特に対極が透明の場合には、対極の抵抗を下げる目的で金属リードを用いるのが好ましい。なお、好ましい金属リードの材質および設置方法、金属リード設置による入射光量の低下等は導電性支持体の場合と同じである。
【００７１】
（E）その他の層
対極と導電性支持体の短絡を防止するため、予め導電性支持体と感光層の間に緻密な半導体の薄膜層を下塗り層として塗設しておくことが好ましく、電荷輸送層に電子輸送材料や正孔輸送材料を用いる場合は、特に有効である。下塗り層として好ましいのはTiO₂、SnO₂、Fe₂O₃、WO₃、ZnO、Nb₂O₅であり、さらに好ましくはTiO₂である。下塗り層は、例えばElectrochim. Acta 40巻, 643-652頁(1995)に記載されているスプレーパイロリシス法の他、スパッタ法等により塗設することができる。下塗り層の好ましい膜厚は5〜1000nmであり、10〜500nmがさらに好ましい。
また、電極として作用する導電性支持体と対極の一方または両方の外側表面、導電層と基板の間または基板の中間に、保護層、反射防止層等の機能性層を設けても良い。これらの機能性層の形成には、その材質に応じて塗布法、蒸着法、貼り付け法等を用いることができる。
【００７２】
（F）光電変換素子の内部構造の具体例
上述のように、光電変換素子の内部構造は目的に合わせ様々な形態が可能である。大きく２つに分ければ、両面から光の入射が可能な構造と、片面からのみ可能な構造が可能である。図２〜図９は、本発明に好ましく適用できる光電変換素子の内部構造のいくつかを部分断面図として例示したものである。
図２に示した態様は、透明導電層10aと透明対極導電層40aとの間に、電着層を含む感光層20と、電荷輸送層30とを介在させたものであり、両面から光が入射する構造となっている。図３に示した態様は、透明基板50a上に一部金属リード11を設け、さらに透明導電層10aを設け、下塗り層60、感光層20、電荷輸送層30および対極導電層40をこの順で設け、さらに支持基板50を配置したものであり、導電層側から光が入射する構造となっている。図４に示した態様は、支持基板50上にさらに導電層10を有し、下塗り層60を介して感光層20を設け、さらに電荷輸送層30と透明対極導電層40aとを設け、一部に金属リード11を設けた透明基板50aを、金属リード11側を内側にして配置したものであり、対極側から光が入射する構造である。図５に示した態様は、透明基板50a上に一部金属リード11を設け、さらに透明導電層10a（または40a）を設けたもの１組の間に下塗り層60と感光層20と電荷輸送層30とを介在させたものであり、両面から光が入射する構造である。図６に示した態様は、透明基板50a上に透明導電層10a、下塗り層60、感光層20、電荷輸送層30および対極導電層40を設け、この上に支持基板50を配置したものであり導電層側から光が入射する構造である。図７に示した態様は、支持基板50上に導電層10を有し、下塗り層60を介して感光層20を設け、さらに電荷輸送層30および透明対極導電層40aを設け、この上に透明基板50aを配置したものであり、対極側から光が入射する構造である。図８に示した態様は、透明基板50a上に透明導電層10aを有し、下塗り層60を介して感光層20を設け、さらに電荷輸送層30および透明対極導電層40aを設け、この上に透明基板50aを配置したものであり、両面から光が入射する構造となっている。図９に示した態様は、支持基板50上に導電層10を設け、下塗り層60を介して感光層20を設け、さらに固体の電荷輸送層30を設け、この上に一部対極導電層40または金属リード11を有するものであり、対極側から光が入射する構造となっている。
【００７３】
〔２〕光電池
本発明の光電池は、上記光電変換素子に外部負荷で仕事をさせるようにしたものである。
光電池のうち、電荷輸送材料が主としてイオン輸送材料からなる場合を、特に光電気化学電池と呼び、また、太陽光による発電を主目的とする場合を太陽電池と呼ぶ。光電池は、構成物の劣化や内容物の揮散を防止するために、側面をポリマーや接着剤等で密封するのが好ましい。導電性支持体および対極にリードを介して接続される外部回路自体は公知のもので良い。本発明の光電変換素子を太陽電池に適用する場合、そのセル内部の構造は、基本的に上述した光電変換素子の構造と同じである。また、本発明の色素増感型太陽電池は、従来の太陽電池モジュールと基本的には同様のモジュール構造をとりうる。太陽電池モジュールは、一般的には金属、セラミック等の支持基板の上にセルが構成され、その上を充填樹脂や保護ガラス等で覆い、支持基板の反対側から光を取り込む構造をとるが、支持基板に強化ガラス等の透明材料を用い、その上にセルを構成してその透明の支持基板側から光を取り込む構造とすることも可能である。具体的には、スーパーストレートタイプ、サブストレートタイプ、ポッティングタイプと呼ばれるモジュール構造、アモルファスシリコン太陽電池などで用いられる基板一体型モジュール構造等が知られており、本発明の色素増感型太陽電池も使用目的や使用場所および環境により、適宜これらのモジュール構造を選択できる。具体的には、特願平11-8457に記載の構造や態様とすることが好ましい。
【００７４】
［実施例１］
以下、本発明を実施例によって具体的に説明する。
本実施例では、図４の層構成からなる透明なシート型光電池を下記の手順で組み立てた。
１．透明導電性支持体の作製
厚さ１．９ｍｍの無アルカリガラスの基板に、ＣＶＤ法によってフッ素ドープ型の二酸化スズを全面に均一にコーティングし、厚さ６００ｎｍ、面抵抗約１５Ω／□、光透過率（５００ｎｍ）が８５％の導電性二酸化スズ膜を片面に被覆した透明導電性支持体を形成した。
【００７５】
２．半導体微粒子の準備
半導体微粒子Ａ〜Ｅの５種類の粒子試料を下記のように調製した。
(i)粒子Ａ
バーブ（Ｃ．Ｊ．Ｂａｒｂｅ）らのＪ．Ａｍ．Ｃｅｒａｍｉｃ Ｓｏｃ．80巻，３１５７頁の論文に記載の製造方法に従い、チタン原料にチタニウムテトライソプロポキシドを用い、オートクレーブ中での重合反応の温度を２３０℃に設定して二酸化チタン濃度１１重量％のアナターゼ型二酸化チタンの分散液を合成した。得られた二酸化チタン粒子の一次粒子のサイズは１０〜３０ｎｍであった。得られた分散液を、超遠心分離機にかけて、粒子を分離し、凝集物をメノウ乳鉢上で粉砕して粉末とした。
(ii)粒子Ｂ
日本アエロジル社製のＰ−２５を使用した。気相中の焼成法によって作られた一次粒径２０ｎｍ、ＢＥＴ法で求めた比表面積５０ｍ²/ｇ、アナターゼ含有率７７％の酸化チタン（ＴｉＯ₂）粒子である。
【００７６】
(iii)粒子Ｃ
アルドリッチ社製のアナターゼ型酸化チタン（ＴｉＯ₂）を使用した。粒径の分布が０．１〜３μｍ、アナターゼ含有率９９％の白色度の高い粒子である。
(iv)粒子Ｄ
平均粒径３５μｍ（ＢＥＴ法による）、ＢＥＴ法で求めた比表面積３０ｍ²/ｇ、の六方晶系多面体からなる気相法で合成された酸化亜鉛（ＺｎＯ）粒子である。
(Ｖ)粒子Ｅ
平均粒径１５μｍ（ＢＥＴ法による）、ＢＥＴ法で求めた比表面積７０ｍ² /ｇ、の気相法で合成された正方晶系の酸化スズ（ＳｎＯ₂）粒子である。
【００７７】
３．半導体微粒子層の作製（電着）
上記２で得た５種類の微粒子を、それぞれアセトニトリルとtert−ブタノール（１：１）の乾燥した混合溶媒に０．０３５ｇ／ｍＬの添加量で分散し、白色の分散液としたあと、室温のもとで、超音波で５分間攪拌処理した。超音波攪拌による温度上昇は小さいので特に制御しなかった。電着用基板電極ならびに電着用対極として上記の酸化スズ透明導電性支持体を２枚用意し、両者を厚さ０．３ｍｍのテフロンフィルムのフレームを使って導電層側を対向させた。２枚の電極の間隙に、上記の半導体微粒子分散液を注入して静置し、両電極間にＤＣ電源を用いて、下記の電圧を印加して、電着を行った。
【００７８】

【００７９】
得られた電着層を室温下で３０分間乾燥した後に、１２０℃のもとで、乾燥空気中で加熱した。電着による収率（電着された粒子／全粒子）は粒子Ａ、Ｂ、Ｃはほぼ１００％であったが、粒子ＤとＥは７０〜９０％の範囲で不安定であった。
このようにして得られた電着層の粒子担持量は、粒子Ａ〜Ｅをそれぞれ担持した基板Ａ〜Ｅについて、基板Ａ：９．９ｇ／ｍ²、基板Ｂ：１０．０ｇ／ｍ²、基板Ｃ：９．８ｇ／ｍ²、基板Ｄ：８．０ｇ／ｍ²、基板Ｅ：８．２ｇ／ｍ²となった。また、電着層の平均膜厚みの結果は、基板Ａ：７μｍ、基板Ｂ：８μｍ、基板Ｃ：９μｍ、基板Ｄ：６μｍ、基板Ｅ：５．５μｍであった。
電着基板の一部は、さらに１００Ｗの水銀灯紫外線光源のＵＶ光に１５０℃のもとで１時間露光して、後処理を行った。
【００８０】
４．色素吸着溶液の調製
長波長側に７５０ｎｍまで吸収を持ち、青色〜緑色領域に吸収ピークを有する増感色素として、前述具体例のＲｕ錯体色素（色素Ｒ−１）を、乾燥したアセトニトリル：ｔ−ブタノール：エタノール（２：１：１）の混合溶媒に濃度３×１０^-4モル／リットルに溶解した。 この色素溶液に添加剤として、p-Ｃ₉Ｈ₁₉−Ｃ₆Ｈ₄−Ｏ−（ＣＨ₂ＣＨ₂−Ｏ）₃−（ＣＨ₂）4−ＳＯ₃Ｎaの構造の有機スルホン酸誘導体を０．０２５モル／リットルの濃度となるように溶解して色素吸着用の溶液を調製した。
【００８１】
５．色素の吸着
上記の半導体微粒子電着基板Ａ〜Ｅを、上記の吸着用色素溶液に浸漬して、攪拌下４０℃で３時間放置した。このようにして微粒子電着層に色素を吸着させたのち、電極をアセトニトリルで洗浄し、感光層に用いる色素増感電極を作製した。
【００８２】
６．光電気化学電池の作製
色素増感半導体電極の電着層を直径約１．１ｃｍの円形部分を残して掻き落として、受光面積１．０ｃｍ²（直径約１．１ｃｍ）の円形の受光層を形成した。この電極に対して、対極の白金蒸着ガラス基板を、熱圧着性のポリエチレンフイルム製のフレーム型スペーサー（厚さ２０μｍ）を挿入して重ね合わせ、スペーサー部分を１２０℃に加熱し両基板を圧着した。さらにセルのエッジ部をエポキシ樹脂接着剤でシールした。対極の基板のコーナー部にあらかじめ設けた電解液注液用の小孔を通して、電解質としてY6-2/Y9-1/よう素=15:35:1(重量比)の組成から成る室温溶融塩を基板の小孔から毛細管現象を利用して電極間の空間にしみこませた。以上のセル組立て工程と、電解液注入の工程をすべて上記の露点−６０℃の乾燥空気中で実施した。溶融塩の注入後、真空下でセルを数時間吸引し、多孔質の半導体電極、溶融塩等のセル内部の脱気を行い、最終的に小孔を低融点ガラスで封じた。
同様な方法で、増感色素として、上記の実施例で用いたＲ-１に替えて９００ｎｍまでの可視領域に吸収をもつ長波長色素Ｒ-１０を用いて本発明の透明光電変換素子を作製した。
【００８３】
７．光電変換効率の測定
５００Ｗのキセノンランプ（ウシオ電気）に太陽光シミュレーション用補正フィルター（Ｏｒｉｅｌ社製ＡＭ１．５ｄｉｒｅｃｔ）を装着し、上記光電変換素子に対し、入射光強度が１００ｍＷ/ｃｍ²の模擬太陽光を、半導体微粒子電着層を担持した透明電極の側から照射した。素子は恒温装置のステージ上に密着して固定し、照射中の素子の温度を５０℃に制御した。
電流電圧測定装置（ケースレー製ソースメジャーユニット２３８型）を用いて、素子に印加するＤＣ電圧を１０ｍＶ／秒の定速で走査し、素子の出力する光電流を計測することにより、光電流―電圧特性を測定した。これにより求められた上記の各種素子の光電流密度（Ｊｓｃ）、開放回路起電力（Ｖｏｃ）、エネルギー変換効率(η)を、セルの構成要素（半導体微粒子、増感色素）の内容とともに表１に記載した。
なお、表中には、比較実験として、電着の条件（電着電圧、電着後の加熱処理）を変えて作製した素子の結果も、示した。
【００８４】
【表１】

【００８５】
【表２】

【００８６】
表１の結果から、以下のことが明らかである。
１）本発明の製造法に従った半導体微粒子の電着層を用いて、電極の高温焼成を行うことなく、太陽電池としても実用に適したエネルギー変換効率が得られる。
２）電着に用いる電場の条件として、強度の絶対値が５０V／ｃｍ以下の低い電場を用いた電着では、基板上の電着量が減り、その結果として性能（特にJsc）が低下する傾向がみられる。また、絶対値が３００V／ｃｍ以上の高い電場を用いた電着では、電着量の低下は起こらないものの、性能の低下する傾向がみられた。この理由は不明であるが、基板の導電膜の電気化学的劣化によって基板抵抗が上昇しフィルファクター（ＦＦ）に影響が出たものと推定される。
３）電着膜に加熱処理を施した場合は性能の改善が見られ、加熱処理とＵＶ光照射処理を同時に施したものにはさらなる性能の改善が見られる。
【００８７】
［実施例２］
実施例１で用いた透明導電性ガラス支持体と白金蒸着ガラス（対極）に代えて、下記のプラスチック製の透明導電性シートをそれぞれ用いた以外は、実施例１と同じ工程と操作によって、色素増感半導体作用極と対極の両方がプラスチック基板から成るプラスチック製のシート型光電変換セルを作製した。
１．作用極用の透明導電性プラスチックシート
厚さ０．４ｍｍのポリエステルシートの片面に、導電性の酸化インジウムスズ（ＩＴＯ）の薄膜を厚さ２００ｎｍで均一にコーティングして作ったフレキシブルな基板であり、面抵抗約２０Ω／□、光透過率（５００ｎｍ）が８８％の透明導電性プラスチックシート。
２．対極極用の導電性プラスチックシート
厚さ０．４ｍｍのポリイミド製カプトンフイルムの片面に、真空スパッタリング法によって白金の膜を厚さ３００ｎｍで均一に被覆した、面抵抗約５Ω／□、の導電性プラスチックシート。
【００８８】
表２に、これらのプラスチック電極基板を用いて組み立てた光電気化学電池の構成と性能を示した。表１に示したガラス基板を用いた結果に比べると、ＩＴＯ／ポリエステル基板の面抵抗が高いこと（導電性が低いこと）に起因し、ＦＦが下がった結果として、ガラス基板を用いたセルほどの性能は得られていないものの、実用レベルの光電変換性能が得られていることがわかる。また、特にこれらのセルは、ガラスを用いないことで、柔軟性を付与したフレキシブルセルとしてのメリットを有している。
【００８９】
【表３】

【００９０】
以上のように、本発明の半導体微粒子の電着層を感光層として用いることによって、色素増感型の光電変換素子を焼成工程を含まない安価な手段で作ることができるとともに、太陽電池としても有用な性能を備えた素子をプラスチックシートを含む各種の基板を用いて提供することが出来る。
【００９１】
【発明の効果】
本発明によって、エネルギー変換効率とコストパーフォーマンスに優れた色素増感型の光電変換素子ならびに光電気化学電池が得られる。
【図面の簡単な説明】
【図１】 本発明の好ましい光電変換素子の構造を示す部分断面図である。
【図２】 本発明の別の態様の光電変換素子の構造を示す部分断面図である。
【図３】 本発明のさらに別の態様の光電変換素子の構造を示す部分断面図である。
【図４】 本発明のさらに別の態様の光電変換素子の構造を示す部分断面図である。
【図５】 本発明のさらに別の態様の光電変換素子の構造を示す部分断面図である。
【図６】 本発明のさらに別の態様の光電変換素子の構造を示す部分断面図である。
【図７】 本発明のさらに別の態様の光電変換素子の構造を示す部分断面図である。
【図８】 本発明のさらに別の態様の光電変換素子の構造を示す部分断面図である。
【図９】 本発明のさらに別の態様の光電変換素子の構造を示す部分断面図である。
【符号の説明】
10・・・導電層
10a・・・透明導電層
11・・・金属リード
20・・・感光層
21・・・半導体微粒子
22・・・色素
23・・・電荷輸送材料
30・・・電荷輸送層
40・・・対極導電層
40a・・・透明対極導電層
50・・・基板
50a・・・透明基板
60・・・下塗り層[0001]
BACKGROUND OF THE INVENTION
The present invention relates to the technical fields of photoelectric conversion and optical sensing, and relates to a photoelectric conversion element manufactured by a low-cost manufacturing process that does not include high-temperature baking. Furthermore, the present invention relates to a photovoltaic cell using the same.
[0002]
[Prior art]
Photoelectric conversion elements are widely used in both the energy conversion and optical sensing industrial fields, and so far, solid elements typified by Si pn junctions and compound semiconductor heterojunctions have been used as high-sensitivity elements. I came. Photovoltaic (PV) cells for photovoltaic power generation are important issues for high sensitivity and durability, and are currently compound semiconductors such as single crystal silicon, polycrystalline silicon, amorphous silicon, cadmium telluride and indium copper selenide Photovoltaic cells using these solid junctions are the main technology. However, since these photovoltaic cells all require crystal formation at high temperatures or lamination of high-purity thin films using vacuum technology, there is a problem that the energy consumption of the manufacturing process is large and the cost is high. It is out. Amorphous silicon solar cells, which are considered to be the most powerful in terms of performance and cost ratio, can use visible light up to 800 nm, and provide an open circuit voltage of 0.7 V or more and an energy conversion efficiency close to 10%. However, a vacuum deposition process is required, and there is a limit to significant cost reduction.
[0003]
Under such circumstances, photoelectric conversion elements and solar cells using dye-sensitized semiconductor fine particles disclosed in Nature (Vol. 353, 737-740, 1991) and US Pat. Has been. A typical example is a so-called wet solar cell, an electrochemical photovoltaic cell comprising a titanium dioxide porous thin film spectrally sensitized using a ruthenium complex having excellent light resistance as a dye. The advantage of this wet solar cell is that it can provide a photoelectric conversion element at low cost using an inexpensive oxide semiconductor such as titanium dioxide. The second advantage is that the wavelength of light absorption is selected according to the type of dye used. Or can be extended to longer wavelengths. The porous semiconductor fine particle layer, which is a structural feature of this system, is an essential element for increasing the amount of dye adsorption and realizing high light absorption, and usually disperses a highly viscous dispersion containing semiconductor fine particles. It is obtained by applying the material together with the material on the electrode substrate and firing the material at a relatively high temperature (400 to 500 ° C.) to remove the dispersed material. However, the high-temperature firing step not only hinders cost reduction, but also limits the type of support that supports the semiconductor fine particle layer, so that it is difficult to form an electrode layer on a plastic substrate or the like.
[0004]
[Problems to be solved by the invention]
An object of the present invention is to provide a dye-sensitized semiconductor type photoelectric conversion element and a photovoltaic cell that have high energy conversion efficiency and can be manufactured at low cost.
[0005]
[Means for Solving the Problems]
  The object of the present invention has been achieved by the following matters specifying the present invention and preferred embodiments thereof.
(1) A method for producing a photoelectric conversion element comprising a laminated structure including a conductive support having a conductive layer, a semiconductor fine particle layer, a charge transport layer and a counter electrode, wherein the semiconductor fine particles are electrophoresed on the conductive layer of the conductive support. A step of forming the semiconductor fine particle layer by adhering to the surface, and the formed semiconductor fine particle layerUnder the irradiation of light absorbed by semiconductor fine particlesThe manufacturing method of the photoelectric conversion element characterized by including the process heated at 100 to 250 degreeC.
(2) The method for producing a photoelectric conversion element according to the above (1), wherein the electrophoresis is performed using a semiconductor fine particle dispersion containing no electrolyte.
(3) The photoelectric conversion element according to (1) or (2), wherein the electrophoresis is performed in a direct current electric field, and the strength of the electric field is 50 V / cm or more and 300 V / cm or less. Production method.
(4) The photoelectric conversion element according to (1) or (2), wherein the electrophoresis is performed in a direct current electric field, and the strength of the electric field is 60 V / cm or more and 200 V / cm or less. Production method.
[0006]
(5(1) to (1) above, wherein the conductive layer of the conductive support contains tin oxide.4The manufacturing method of the photoelectric conversion element in any one of.
(6The semiconductor fine particles are semiconductors selected from titanium oxide, zinc oxide, tin oxide, tungsten oxide, niobium oxide, and a composite of two or more thereof. (5The manufacturing method of the photoelectric conversion element in any one of.
[0007]
(7The semiconductor fine particles are semiconductors selected from titanium oxide, zinc oxide, tin oxide, and a composite of two or more thereof.6) The photoelectric conversion element according to any one ofManufacturing method.
(8(1) to (1) above, wherein the semiconductor fine particle layer is sensitized with a dye.7) The photoelectric conversion element according to any one ofManufacturing method.
(9(1) to (1) above, wherein the charge transfer layer contains an electrolyte.8) The photoelectric conversion element according to any one ofManufacturing method.
(10(1) to (1) above, wherein the charge transfer layer contains a molten salt electrolyte.9) The photoelectric conversion element according to any one ofManufacturing method.
(11(1) to (1), wherein the conductive support is a plastic support having a conductive layer.10) The photoelectric conversion element according to any one ofManufacturing method.
(12) A photoelectric conversion element manufactured by the manufacturing method according to any one of (1) to (11).
(13)the above(12)A photovoltaic cell using the photoelectric conversion element described in 1.
(14)the above(12)A solar cell using the photoelectric conversion element described in 1.
(15)the above(12)An optical sensor using the photoelectric conversion element described in 1.
The present invention relates to the above (1) to (3), (5), (6), (8), and (10) to (13), but other matters are also described for reference.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
The present invention is described in detail below.
The photoelectric conversion element of the present invention uses a layer of semiconductor fine particles as a photosensitive electrode, and is formed by bonding a charge transport layer such as an electrolyte to the semiconductor fine particle layer. It is characterized by being formed by a kind of electrodeposition using the adhesion of a charged substance (charged semiconductor fine particles) to the substrate by electrophoresis instead of the method according to.
[0009]
[1] Photoelectric conversion element
The main points of the photoelectric conversion element of the present invention will be described with reference to the drawings. FIG. 1 is a partial cross-sectional view showing a typical structure of the photoelectric conversion element of the present invention. In FIG. 1, a conductive layer 10, an undercoat layer 60, a photosensitive layer (semiconductor fine particle layer) 20, a charge transport layer 30, and a counter electrode conductive layer 40 are laminated in this order, and the photosensitive layer 20 is sensitized with a dye 22. And a charge transport material 23 that has permeated into the gaps between the semiconductor fine particles 21. The charge transport material 23 is composed of the same components as the material used for the charge transport layer 30. Further, a substrate 50 may be provided as a base for the conductive layer 10 and / or the counter electrode conductive layer 40 in order to impart strength to the photoelectric conversion element. In the present invention, the layer composed of the conductive layer 10 and the optional substrate 50 is hereinafter referred to as “conductive support”, and the layer composed of the counter electrode conductive layer 40 and the optional substrate 50 is referred to as “counter electrode”. Note that the conductive layer 10, the counter electrode conductive layer 40, and the substrate 50 in FIG. 1 may be the transparent conductive layer 10a, the transparent counter electrode conductive layer 40a, and the transparent substrate 50a, respectively. A photocell is made for the purpose of generating electrical work by connecting this photoelectric conversion element to an external load (power generation), and a photosensor is made for the purpose of sensing optical information. Among the photovoltaic cells, the case where the charge transport material 23 is mainly made of an ion transport material is particularly called a photoelectrochemical cell, and the case where the main purpose is power generation by sunlight is called a solar cell.
[0010]
In the photoelectric conversion element of the present invention shown in FIG. 1, when the semiconductor fine particles are n-type, the light incident on the photosensitive layer 20 containing the semiconductor fine particles 21 sensitized by the dye 22 excites the dye 22 and the like. The high-energy electrons in the dye 22 and the like thus transferred are transferred to the conduction band of the semiconductor fine particles 21, and further reach the conductive layer 10 by diffusion. At this time, the molecule such as the dye 22 is an oxidant. In the photovoltaic cell, electrons in the conductive layer 10 return to an oxidant such as the dye 22 through the counter electrode conductive layer 40 and the charge transport layer 30 while working in an external circuit, and the dye 22 is regenerated. The photosensitive layer 20 functions as a negative electrode (photoanode), and the counter electrode 40 functions as a positive electrode. At each layer boundary (for example, the boundary between the conductive layer 10 and the photosensitive layer 20, the boundary between the photosensitive layer 20 and the charge transport layer 30, the boundary between the charge transport layer 30 and the counter conductive layer 40, etc.) They may be diffusively mixed with each other. Each layer will be described in detail below.
[0011]
(A) Conductive support
The conductive support is composed of (1) a single layer of a conductive layer, or (2) two layers of a conductive layer and a substrate. In the case of (1), a material that can sufficiently maintain strength and hermeticity is used as the conductive layer. For example, a metal material (platinum, gold, silver, copper, zinc, titanium, aluminum, or the like is included) Alloy) can be used. In the case of (2), a substrate having a conductive layer containing a conductive agent on the photosensitive layer side can be used. Preferred conductive agents include metals (eg, platinum, gold, silver, copper, zinc, titanium, aluminum, indium, etc. or alloys containing these), carbon, or conductive metal oxides (indium-tin composite oxide, tin oxide). And those doped with fluorine or antimony). The thickness of the conductive layer is preferably about 0.02 to 10 μm.
[0012]
The lower the surface resistance of the conductive support, the better. The range of the surface resistance is preferably 50Ω / □ or less, more preferably 20Ω / □ or less. In the present invention, the conductive support serves as a substrate electrode for forming a semiconductor fine particle layer. In the formation of the semiconductor fine particle layer of the present invention, since a voltage of several volts is applied to the substrate electrode, the substrate electrode needs to be electrochemically stable. In this respect, a particularly preferable conductive material is , Tin oxide.
[0013]
When irradiating light from the conductive support side, the conductive support is preferably substantially transparent. “Substantially transparent” means that the transmittance is 10% or more in a part or all of the light in the visible to near infrared region (400 to 1200 nm), preferably 50% or more, 80% or more is more preferable. In particular, it is preferable that the transmittance in a wavelength region where the photosensitive layer is sensitive is high.
[0014]
The transparent conductive support is preferably formed by applying or vapor-depositing a transparent conductive layer made of a conductive metal oxide on the surface of a transparent substrate such as glass or plastic. Preferred as the transparent conductive layer is fluorine dioxide or antimony doped tin dioxide or indium-tin oxide (ITO). As the transparent substrate, a glass substrate such as soda glass which is advantageous in terms of low cost and strength, alkali-free glass which is not affected by alkali elution, and a transparent polymer film which is advantageous in cost and flexibility can be preferably used. Transparent polymer film materials include triacetyl cellulose (TAC), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), syndiotactic polyester (SPS), polyphenylene sulfide (PPS), polycarbonate (PC), polyarylate (PAr), polysulfone (PSF), polyester sulfone (PES), polyimide (PI), polyetherimide (PEI), cyclic polyolefin, brominated phenoxy resin, and the like. In order to ensure sufficient transparency, the amount of conductive metal oxide applied is 1 m of glass or plastic support.²The amount is preferably 0.01 to 100 g.
[0015]
It is preferable to use a metal lead for the purpose of reducing the resistance of the transparent conductive support. The material of the metal lead is preferably a metal such as platinum, gold, nickel, titanium, aluminum, copper, or silver. The metal lead is preferably provided on a transparent substrate by vapor deposition, sputtering or the like, and a transparent conductive layer made of conductive tin oxide or ITO film is preferably provided thereon. The decrease in the amount of incident light due to the installation of the metal lead is preferably within 10%, more preferably 1 to 5%.
[0016]
(B) Photosensitive layer
In the photosensitive layer, the semiconductor acts as a photoconductor, absorbs light, separates charges, and generates electrons and holes. In a dye-sensitized semiconductor, light absorption and the generation of electrons and holes thereby occur mainly in the dye, and the semiconductor particles play a role of receiving and transmitting these electrons (or holes). The semiconductor used in the present invention is preferably an n-type semiconductor in which conductor electrons become carriers under photoexcitation and give an anode current. A semiconductor preferable as a semiconductor material constituting the photosensitive layer in the present invention has a carrier concentration of 10 for conduction.¹⁴-10²⁰Piece / cm^ThreeIt is a semiconductor of the range.
[0017]
(1) Semiconductor
As the semiconductor, a single semiconductor such as silicon or germanium, a III-V group compound semiconductor, a metal chalcogenide (for example, oxide, sulfide, selenide, or a composite thereof), or a compound having a perovskite structure ( For example, strontium titanate, calcium titanate, sodium titanate, barium titanate, potassium niobate, etc.) can be used.
[0018]
Preferred metal chalcogenides include titanium, tin, zinc, iron, tungsten, zirconium, hafnium, strontium, indium, cerium, yttrium, lanthanum, vanadium, niobium, or tantalum oxide, cadmium, zinc, lead, silver, antimony or Bismuth sulfide, cadmium or lead selenide, cadmium telluride and the like. Examples of other compound semiconductors include phosphides such as zinc, gallium, indium, and cadmium, gallium-arsenic or copper-indium selenides, and copper-indium sulfides. Furthermore, MxOySz or M₁xM₂yOz (M, M₁And M₂A composite element such as each of which is a metal element, O is oxygen, and x, y, and z are combinations of which the valence is neutral) can also be preferably used.
[0019]
A preferred specific example of the semiconductor used in the present invention is TiO₂, SnO₂, Fe₂O_Three, WO_Three, ZnO, Nb₂O_Five, CdS, ZnS, PbS, Bi₂S_Three, CdSe, CdTe, SrTiO_Three, GaP, InP, GaAs, CuInS₂, CuInSe₂And more preferably TiO₂, ZnO, SnO₂, WO_ThreeOr Nb₂O_FiveAnd particularly preferably TiO₂, SnO₂Or ZnO, most preferably TiO₂It is. TiO₂TiO containing 70% or more of anatase type crystals₂And particularly preferably 100% anatase type TiO₂It is. It is also effective to dope metals for the purpose of increasing the electronic conductivity in these semiconductors. As the metal to be doped, divalent and trivalent metals are preferable. In order to prevent a reverse current from flowing from the semiconductor to the charge transport layer, it is also effective to dope a monovalent metal into the semiconductor.
[0020]
The particle size of the semiconductor fine particles is generally on the order of nm to μm, but the average particle size of the primary particles obtained from the diameter when the projected area is converted into a circle is preferably 5 to 200 nm, more preferably 8 to 100 nm. preferable. The average particle size of the semiconductor fine particles (secondary particles) in the dispersion is preferably 0.01 to 30 μm. Two or more kinds of fine particles having different particle size distributions may be mixed. In this case, the average size of the small particles is preferably 25 nm or less, more preferably 10 nm or less. For the purpose of improving the light capture rate by scattering incident light, it is also preferable to mix semiconductor particles having a large particle diameter, for example, about 100 nm or more and about 300 nm.
[0021]
Semiconductor fine particles are prepared by Sakuo Sakuo's "Sol-gel Method Science" Agne Jofusha (1998), Technical Information Association "Sol-gel Method Thin Film Coating Technology" (1995), etc. The sol-gel method described, Tadao Sugimoto's "Synthesis of monodisperse particles by the new synthesis gel-sol method and size morphology control", Materia, Vol. 35, No. 9, pp. 1012-1018 (1996) The gel-sol method described in 1 is preferred. Also preferred is a method developed by Degussa to produce an oxide by high-temperature hydrolysis of chloride in an oxyhydrogen salt.
When the semiconductor fine particles are titanium oxide, the sol-gel method, gel-sol method, and high-temperature hydrolysis method in oxyhydrogen salt of chloride are all preferred, but Kiyoshi Manabu's “Titanium oxide properties and applied technology” The sulfuric acid method and the chlorine method described in Gihodo Publishing (1997) can also be used. Further, as a sol-gel method, the method described in Journal of American Ceramic Society, Volume 80, No. 12, pages 3157-3171 (1997) of Barbe et al., Barnside The method described in Chemistry of Materials, Vol. 10, No. 9, pages 2419-2425 is also preferable.
[0022]
(2) Formation of semiconductor fine particle layer
The formation of the semiconductor fine particle layer of the present invention (the electrodeposition method of the present invention) is carried out by causing the semiconductor fine particles to migrate to adhere to the conductive layer side of the conductive support. Usually, it is performed according to the following process and conditions.
First, semiconductor fine particles are added to an appropriate low-conductivity solvent and uniformly dispersed so as not to aggregate. In order to lower the conductivity, it is important that the solvent does not substantially contain a dissociable electrolyte salt and does not contain an electrochemically active redox compound so as not to hinder the formation of a semiconductor fine particle layer. . The solvent is preferably pure water, a polar organic solvent such as alcohol, acetonitrile, or THF, a nonpolar organic solvent such as hexane or chloroform, or a mixed solvent thereof. The particle content of the dispersion is preferably in the range of 0.01 g to 0.1 g / mL.
Secondly, a substrate electrode to be electrodeposited (for example, a support having a conductive tin oxide layer) and a counter electrode for electrodeposition are opposed in parallel at a constant interval, and the dispersion liquid is injected into the gap. The distance between both electrodes is usually 0.1 mm to 2 mm, preferably 0.2 mm to 0.5 mm.
Third, a DC voltage is applied between both electrodes. Specifically, the substrate electrode side is set to be positive or negative depending on the property (surface charge) of the particles, and the applied voltage is 50 V / cm to 300 V / cm, preferably 60 V / cm to 200 V / cm. Set to be strong and apply for 1 to 10 minutes. As a result, the semiconductor fine particles first migrate to the substrate electrode by electrophoresis, and then adhere to the electrode. Since the temperature dependence of electrophoresis is relatively small, it is not necessary to strictly control the temperature, and electrophoresis may be performed at room temperature.
As described above, a uniform semiconductor fine particle layer having an arbitrary thickness can be formed on the substrate electrode by selecting the concentration of the dispersion and the electrode interval. The thickness of the semiconductor layer formed by the electrodeposition method of the present invention is preferably 2 to 20 μm.
[0023]
The layer of semiconductor fine particles is not limited to a single layer, and semiconductor fine particles having different particle sizes and types can be electrodeposited over a plurality of layers, or layers having different thicknesses can be electrodeposited.
Moreover, a semiconductor fine particle layer, for example, a coating film, formed by a method different from electrodeposition can be provided on the electrodeposition layer. Conversely, an electrodeposition layer can be provided on the coating film.
[0024]
A preferable thickness of the entire semiconductor fine particle layer is 0.1 to 100 μm. When used in a solar cell, the thickness of the semiconductor fine particle layer is preferably 1 to 30 μm, and more preferably 2 to 25 μm. Semiconductor fine particle support 1m²The hit load is preferably 0.5 to 400 g, more preferably 5 to 100 g.
[0025]
The semiconductor fine particle layer of the present invention is preferably subjected to a heat treatment in order to enhance the electronic contact between the semiconductor fine particles and improve the adhesion to the support.
Although it is effective to use a temperature of 100 ° C. to 400 ° C. as the heating temperature range, it is preferable for the purpose of reducing adverse effects (deformation, alteration, etc.) due to heating of the conductive support (conductive layer and support). The temperature range is 100 ° C to 250 ° C. When using a support having a low melting point or softening point, such as a polymer film, as the transparent support, the heat treatment temperature is preferably as low as possible (200 ° C. or less). Moreover, the photoelectric conversion element produced by the method of the present invention can obtain sufficient conversion efficiency even at low temperature heating. The heat treatment time varies depending on the heat treatment temperature and the type of semiconductor particles, but is usually a time optimized in the range of 10 minutes to 10 hours.
In the present invention, it is preferable that the semiconductor fine particle layer is irradiated with light absorbed by the fine particles during the heat treatment. Thus, by photoexciting the semiconductor, it is considered that impurities mixed in the fine particle layer can be photodecomposed to clean the fine particle layer and enhance physical bonding between the fine particles. The light to be irradiated is preferably ultraviolet light that is strongly absorbed by the semiconductor.
[0026]
The semiconductor fine particle layer preferably has a large surface area for the purpose of increasing the adsorption amount of the dye, and the ratio of the surface area to the projected area of the layer is preferably 10 times or more, and more preferably 100 times or more. Preferably there is. The upper limit is not particularly limited, but is usually about 1000 times.
[0027]
(3) Dye
As the kind of the dye for sensitizing the semiconductor fine particles, an organometallic complex dye, a porphyrin dye, a phthalocyanine dye or a methine dye is preferable. These dyes can be used in a mixture of two or more in order to widen the wavelength range of photoelectric conversion as much as possible and increase the conversion efficiency. Further, the dye to be mixed and its ratio can be selected so as to match the wavelength range and intensity distribution of the target light source.
[0028]
Such a dye preferably has an appropriate interlocking group capable of adsorbing to the surface of the semiconductor fine particles. Preferred linking groups include COOH groups, OH groups, SO₃H group, -P (O) (OH)₂Group or -OP (O) (OH)₂And chelating groups having π conductivity such as oxime groups, dioxime groups, hydroxyquinoline groups, salicylate groups or α-ketoenolate groups. Among them, COOH group, -P (O) (OH)₂Group or -OP (O) (OH)₂The group is particularly preferred. These groups may form a salt with an alkali metal or the like, or may form an internal salt. In the case of a polymethine dye, if the methine chain contains an acidic group as in the case where the methine chain forms a squarylium ring or a croconium ring, this part may be used as a linking group.
[0029]
Hereinafter, preferred sensitizing dyes used in the photosensitive layer will be specifically described.
(A) Organometallic complex dye
When the dye is a metal complex dye, a metal phthalocyanine dye, a metal porphyrin dye or a ruthenium complex dye is preferable, and a ruthenium complex dye is particularly preferable. Examples of ruthenium complex dyes include, for example, U.S. Pat. / 50393, JP-A 2000-26487, and the like.
[0030]
Further, the ruthenium complex dye used in the present invention has the following general formula (I):
(A1) pRu (B-a) (B-b) (B-c) (I)
Is preferably represented by: In the general formula (I), A1 represents a monodentate or bidentate ligand, Cl, SCN, H₂Preference is given to ligands selected from the group consisting of O, Br, I, CN, NCO and SeCN, and derivatives of β-diketones, oxalic acid and dithiocarbamic acid. p is an integer of 0-3. B-a, B-b and B-c are each independently represented by the following formulas B-1 to B-10:
[0031]
[Chemical 1]

[0032]
(However, R_aRepresents a hydrogen atom or a substituent. Examples of the substituent include a halogen atom, a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted aralkyl group having 7 to 12 carbon atoms, and a carbon atom. Examples of the substituted or unsubstituted aryl group of 6 to 12 or the above-mentioned acidic groups (these acidic groups may form a salt) and chelating groups are included. The alkyl part of the alkyl group and the aralkyl group is It may be linear or branched, and the aryl part of the aryl group and aralkyl group represents an organic ligand selected from compounds represented by a single ring or a polycycle (fused ring, ring assembly). B-a, B-b and B-c may be the same or different, and may be any one or two.
[0033]
Although the preferable specific example of an organometallic complex pigment | dye is shown below, this invention is not limited to these.
[0034]
[Chemical 2]

[0035]
[Chemical Formula 3]

[0036]
[Formula 4]

[0037]
(B) Methine dye
Preferred methine dyes for use in the present invention are polymethine dyes such as cyanine dyes, merocyanine dyes, squarylium dyes. Examples of polymethine dyes preferably used in the present invention include JP-A-11-35836, JP-A-11-67285, JP-A-11-86916, JP-A-11-97725, JP-A-11-158395, and JP-A-11. -163378, JP-A-11-214730, JP-A-11-214731, JP-A-11-238905, JP-A2000-26487, European Patents 892411, 911841, and 991092 It is a pigment. Specific examples of preferable methine dyes are shown below.
[0038]
[Chemical formula 5]

[0039]
(4) Adsorption of dye to semiconductor fine particles
In order to adsorb the dye to the semiconductor fine particles, a method of immersing a conductive support having a well-dried semiconductor fine particle layer in a dye solution or coating the dye fine solution on the semiconductor fine particle layer can be used. In the former case, an immersion method, a dip method, a roller method, an air knife method or the like can be used. In the case of the immersion method, the adsorption of the dye may be performed at room temperature or may be performed by heating and refluxing as described in JP-A-7-249790. Examples of the latter application method include a wire bar method, a slide hopper method, an extrusion method, a curtain method, a spin method, and a spray method. Preferred solvents for dissolving the dye include, for example, alcohols (methanol, ethanol, t-butanol, benzyl alcohol, etc.), nitriles (acetonitrile, propionitrile, 3-methoxypropionitrile, etc.), nitromethane, halogenated compounds, etc. Hydrocarbon (dichloromethane, dichloroethane, chloroform, chlorobenzene, etc.), ethers (diethyl ether, tetrahydrofuran, etc.), dimethyl sulfoxide, amides (N, N-dimethylformamide, N, N-dimethylacetamide, etc.), N-methyl Pyrrolidone, 1,3-dimethylimidazolidinone, 3-methyloxazolidinone, esters (ethyl acetate, butyl acetate, etc.), carbonates (diethyl carbonate, ethylene carbonate, propylene carbonate, etc.), ketones (acetone, 2-butanone) , Cyclohexanone, etc.), Examples include hydrocarbons (hexane, petroleum ether, benzene, toluene, etc.) and mixed solvents thereof.
[0040]
The total amount of dye adsorbed is the unit surface area of porous semiconductor electrode substrate (1m²) Is preferably from 0.01 to 100 mmol. The amount of the dye adsorbed on the semiconductor fine particles is preferably in the range of 0.01 to 1 mmol per 1 g of the semiconductor fine particles. By using such an amount of dye adsorbed, a sensitizing effect in a semiconductor can be sufficiently obtained. On the other hand, if the amount of the dye is too small, the sensitizing effect becomes insufficient, and if the amount of the dye is too large, the dye not attached to the semiconductor floats, which causes a reduction in the sensitizing effect. In order to increase the adsorption amount of the dye, it is preferable to perform a heat treatment before the adsorption. In order to avoid water adsorbing on the surface of the semiconductor fine particles after the heat treatment, it is preferable to quickly perform the dye adsorption operation at a temperature of the semiconductor electrode substrate of 60 to 150 ° C. without returning to normal temperature. Further, for the purpose of reducing the interaction such as aggregation between the dyes, a colorless compound may be added to the dyes and co-adsorbed on the semiconductor fine particles. Compounds effective for this purpose are compounds having surface active properties and structures, and examples thereof include steroid compounds having a carboxyl group (for example, chenodeoxycholic acid) and sulfonates such as the following examples.
[0041]
[Chemical 6]

[0042]
(C) Charge transport layer
The charge transport layer is a layer containing a charge transport material having a function of replenishing electrons to the oxidant of the dye. Examples of typical charge transport materials that can be used in the present invention include: (i) a solution (electrolyte) in which redox pair ions are dissolved as an ion transport material; So-called gel electrolytes impregnated in the above, molten salt electrolytes containing redox counterions, and solid electrolytes. In addition to charge transport materials that involve ions, (ii) electron transport materials and hole transport materials can also be used as charge transport materials that involve carrier movement in solids. These charge transport materials can be used in combination.
[0043]
(1) Molten salt electrolyte
The molten salt electrolyte is particularly preferable from the viewpoint of achieving both photoelectric conversion efficiency and durability. The molten salt electrolyte is an electrolyte that is liquid at room temperature or has a low melting point. For example, WO95 / 18456, JP-A-8-259543, Electrochemistry, Vol. 65, No. 11, p. 923 (1997) And the like, known electrolytes such as pyridinium salts, imidazolium salts, and triazolium salts described in the above. A molten salt that becomes liquid at 100 ° C. or lower, particularly near room temperature, is preferred.
[0044]
Examples of the molten salt that can be preferably used include those represented by any of the following general formulas (Y-a), (Y-b), and (Y-c).
[0045]
[Chemical 7]

[0046]
Q in general formula (Y-a)_y1Represents an atomic group capable of forming a 5- or 6-membered aromatic cation with a nitrogen atom. Q_y1Is preferably composed of at least one atom selected from the group consisting of carbon atom, hydrogen atom, nitrogen atom, oxygen atom and sulfur atom. Q_y1The 5-membered ring formed by is preferably an oxazole ring, thiazole ring, imidazole ring, pyrazole ring, isoxazole ring, thiadiazole ring, oxadiazole ring, triazole ring, indole ring or pyrrole ring, A thiazole ring or an imidazole ring is more preferable, and an oxazole ring or an imidazole ring is particularly preferable. Q_y1The 6-membered ring formed by is preferably a pyridine ring, pyrimidine ring, pyridazine ring, pyrazine ring or triazine ring, and more preferably a pyridine ring.
[0047]
In general formula (Y-b), A_y1Represents a nitrogen atom or a phosphorus atom.
[0048]
R in general formulas (Y-a), (Y-b) and (Y-c)_y1~ R_y6Each independently represents a substituted or unsubstituted alkyl group (preferably having 1 to 24 carbon atoms, which may be linear or branched or cyclic, such as a methyl group or an ethyl group Propyl group, isopropyl group, pentyl group, hexyl group, octyl group, 2-ethylhexyl group, t-octyl group, decyl group, dodecyl group, tetradecyl group, 2-hexyldecyl group, octadecyl group, cyclohexyl group, cyclopentyl group, etc. ), Or a substituted or unsubstituted alkenyl group (preferably having 2 to 24 carbon atoms, which may be linear or branched, such as vinyl group, allyl group, etc.), more preferably carbon An alkyl group having 2 to 18 atoms or an alkenyl group having 2 to 18 carbon atoms is preferable, and an alkyl group having 2 to 6 carbon atoms is particularly preferable.
[0049]
In addition, R in the general formula (Y-b)_y1~ R_y4Two or more of them connected to each other_y1May form a non-aromatic ring containing R in the general formula (Y-c)_y1~ R_y6Two or more of them may be connected to each other to form a ring structure.
Q in general formulas (Y-a), (Y-b) and (Y-c)_y1And R_y1~ R_y6May have a substituent, and examples of preferable substituents include halogen atoms (F, Cl, Br, I, etc.), cyano groups, alkoxy groups (methoxy group, ethoxy group, methoxyethoxy group, methoxyethoxy group). Ethoxy groups, etc.), aryloxy groups (phenoxy groups, etc.), alkylthio groups (methylthio groups, ethylthio groups, etc.), alkoxycarbonyl groups (ethoxycarbonyl groups, etc.), carbonate groups (ethoxycarbonyloxy groups, etc.), acyl groups (acetyl groups) , Propionyl group, benzoyl group, etc.), sulfonyl group (methanesulfonyl group, benzenesulfonyl group, etc.), acyloxy group (acetoxy group, benzoyloxy group, etc.), sulfonyloxy group (methanesulfonyloxy group, toluenesulfonyloxy group, etc.), Phosphonyl group (such as diethylphosphonyl group), amide group (a Tilamino group, benzoylamino group, etc.), carbamoyl group (N, N-dimethylcarbamoyl group, etc.), alkyl group (methyl group, ethyl group, propyl group, isopropyl group, cyclopropyl group, butyl group, 2-carboxyethyl group, Benzyl group etc.), aryl group (phenyl group, toluyl group etc.), heterocyclic group (pyridyl group, imidazolyl group, furanyl group etc.), alkenyl group (vinyl group, 1-propenyl group etc.), silyl group, silyloxy group etc. Is mentioned.
The compound represented by the general formula (Y-a), (Y-b) or (Y-c) is Q_y1Or R_y1~ R_y6A multimer may be formed via
[0050]
These molten salts may be used singly or as a mixture of two or more, and may be used in combination with a molten salt in which the iodine anion is replaced with another anion. Anions that replace iodine anions include halide ions (Cl^-, Br^-Etc.), SCN^-, BF_Four ^-, PF₆ ^-, ClO_Four ^-, (CF_ThreeSO₂)₂N^-, (CF_ThreeCF₂SO₂)₂N^-, CH_ThreeSO_Three ^-, CF_ThreeSO_Three ^-, CF_ThreeCOO^-, Ph_FourB^-, (CF_ThreeSO₂)_ThreeC^-Etc. are mentioned as preferred examples, such as SCN.^-, CF_ThreeSO_Three ^-, CF_ThreeCOO^-, (CF_ThreeSO₂)₂N^-Or BF_Four ^-It is more preferable that Also, other iodine salts such as LiI and CF_ThreeCOOLi, CF_ThreeAlkali metal salts such as COONa, LiSCN and NaSCN can also be added. The addition amount of the alkali metal salt is preferably about 0.02 to 2% by mass, and more preferably 0.1 to 1% by mass.
[0051]
Specific examples of the molten salt preferably used in the present invention are listed below, but are not limited thereto.
[0052]
[Chemical 8]

[0053]
[Chemical 9]

[0054]
[Chemical Formula 10]

[0055]
Embedded image

[0056]
Embedded image

[0057]
Embedded image

[0058]
The molten salt electrolyte is preferably in a molten state at room temperature, and preferably does not use a solvent. Although the solvent described later may be added, the content of the molten salt is preferably 50% by mass or more, and particularly preferably 90% by mass or more with respect to the entire electrolyte composition. Moreover, it is preferable that 50 mass% or more is an iodine salt among salts.
[0059]
It is preferable to add iodine to the electrolyte composition. In this case, the content of iodine is preferably 0.1 to 20% by mass, and 0.5 to 5% by mass with respect to the entire electrolyte composition. More preferred.
[0060]
(2) Electrolyte
When an electrolytic solution is used for the charge transport layer, the electrolytic solution is preferably composed of an electrolyte, a solvent, and an additive. The electrolyte of the present invention is I₂And iodide (as iodide, LiI, NaI, KI, CsI, CaI₂ Metal iodides such as tetraalkylammonium iodide, pyridinium iodide, imidazolium iodide and the like quaternary ammonium compounds such as iodine salts), Br₂And bromide combinations (LiBr, NaBr, KBr, CsBr, CaBr as bromides)₂ Metal bromide such as tetraalkylammonium bromide, pyridinium bromide, bromide salts of quaternary ammonium compounds), metal complexes such as ferrocyanate-ferricyanate and ferrocene-ferricinium ions, sodium polysulfide, Sulfur compounds such as alkylthiol-alkyldisulfides, viologen dyes, hydroquinone-quinones, and the like can be used. I among them₂An electrolyte that combines an iodine salt of a quaternary ammonium compound such as LiI, pyridinium iodide, and imidazolium iodide is preferable. The electrolytes described above may be used in combination.
The preferable concentration of the electrolyte is 0.1M to 10M, more preferably 0.2M to 4M. In addition, when iodine is added to the electrolytic solution, a preferable iodine concentration is 0.01M to 0.5M.
[0061]
The solvent used for the electrolyte is desirably a compound having a low viscosity and improving ion mobility, or having a high dielectric constant and an effective carrier concentration, thereby exhibiting excellent ion conductivity. Examples of the solvent include carbonate compounds such as ethylene carbonate and propylene carbonate, heterocyclic compounds such as 3-methyl-2-oxazolidinone, ether compounds such as dioxane and diethyl ether, ethylene glycol dialkyl ether, propylene glycol dialkyl ether, and polyethylene. Chain ethers such as glycol dialkyl ether and polypropylene glycol dialkyl ether, alcohols such as methanol, ethanol, ethylene glycol monoalkyl ether, propylene glycol monoalkyl ether, polyethylene glycol monoalkyl ether, polypropylene glycol monoalkyl ether, ethylene glycol, Propylene glycol, polyethylene glycol, polyp Examples include polyhydric alcohols such as pyrene glycol and glycerin, nitrile compounds such as acetonitrile, glutarodinitrile, methoxyacetonitrile, propionitrile, and benzonitrile, aprotic polar substances such as dimethyl sulfoxide and sulfolane, and water. These can also be mixed and used.
[0062]
Further, in the present invention, tert-butylpyridine as described in Journal of American Ceramic Society (J. Am. Ceram. Soc.), Vol. 80 (12) No. 3157-3171 (1997). In addition, it is preferable to add a basic compound such as 2-picoline or 2,6-lutidine to the aforementioned molten salt electrolyte or electrolytic solution. When adding a basic compound, a preferable concentration range is 0.05M to 2M.
[0063]
(3) Gel electrolyte
In the present invention, the electrolyte is used by gelling (solidifying) the above-mentioned molten salt electrolyte or electrolyte by a technique such as addition of a polymer, addition of an oil gelling agent, polymerization including polyfunctional monomers, or a crosslinking reaction of the polymer. You can also In the case of gelation by adding a polymer, the compounds described in “Polymer Electrolyte Revi ews-1 and 2” (JR MacCallum and CA Vincent, edited by ELSEVIER APPLIED SCIENCE) can be used. In particular, polyacrylonitrile and polyvinylidene fluoride can be preferably used. In the case of gelation by adding an oil gelling agent, published by Chemical Society of Japan, Journal of Industrial Chemistry (J. Chem Soc. Japan, Ind. Chem. Sec.), 46, 779 (1943), Journal of American Chemical Society (J. Am. Chem. Soc.), 111, 5542 (1989), J. Chem. Soc., Chem. Commun., (1993), 390, Angew. Chem., 35, 1949 (1996), Chem. Lett., (1996), p. 885, J. Chm. Soc., Chem. Commun., (1997), p. 545 can be used, but preferred compounds Is a compound having an amide structure in the molecular structure. An example of gelling the electrolytic solution is described in JP-A-11-185863, and an example of gelling the molten salt electrolyte is described in JP-A-2000-58140, which can also be applied to the present invention.
[0064]
Further, when the electrolyte is gelled by a polymer crosslinking reaction, it is desirable to use a polymer containing a crosslinkable reactive group and a crosslinking agent in combination. In this case, preferred crosslinkable reactive groups include amino groups and nitrogen-containing heterocyclic groups (for example, pyridine ring, imidazole ring, thiazole ring, oxazole ring, triazole ring, morpholine ring, piperidine ring, piperazine ring and the like as a skeleton). The preferred cross-linking agent is a bifunctional or higher reagent capable of electrophilic reaction with a nitrogen atom (for example, alkyl halides, halogenated aralkyls, sulfonate esters, acid anhydrides, acids Chlorides, isocyanate compounds, α, β-unsaturated sulfonyl group-containing compounds, α, β-unsaturated carbonyl group-containing compounds, α, β-unsaturated nitrile group-containing compounds, and the like. The cross-linking technique described in the publications of 2000-86724 can also be applied.
[0065]
(4) Hole transport material
In the present invention, instead of an ion conductive electrolyte such as a molten salt, a solid hole transport material that is organic or inorganic or a combination of both can be used.
(A) Organic hole transport material
As an organic hole transporting material applicable to the present invention, J. Hagen et al., Synthetic Metal 89 (1997) 215-220, Nature, Vol. 395, 8 Oct., (1998), 583-585 and WO97 / 10617, JP 59-194393, JP 5-234681, U.S. Pat.No. 4,923,774, JP 4-308688, U.S. Pat. 764,625, JP-A-3-269084, JP-A-4-129271, JP-A-4-175395, JP-A-4-264189, JP-A-4-290851, JP-A-4-364153 No. 5, No. 5-25473, No. 5-239455, No. 5-320634, No. 6-1972, No. 7-138562, No. 7-252474, Special Aromatic amines described in each publication of Kaihei 11-144773 and triphenylene derivatives described in each publication of JP-A-11-149821, JP-A-11-148067, JP-A-11-176489, etc. are preferably used. be able to. Adv. Mater. (1997), 9, N0.7, 557, Angew. Chem. (1995), 34, No. 3, 303-307, American Chemical Society (J. Am. Chem) Soc.), 120, N0.4, (1998), pages 664-672, etc., oligothiophene compounds, K. Murakoshi Oka ,; Chem. Lett. (1997), page 471, polypyrrole Polyacetylene and its derivatives described in “Handbook of Organic Conductive Molecules and Polymers, Volumes 1,2,3,4” (by NALWA, published by WILEY), poly (p-phenylene) and its derivatives, poly (p- Conductive polymers such as (phenylene vinylene) and derivatives thereof, polythienylene vinylene and derivatives thereof, polythiophene and derivatives thereof, polyaniline and derivatives thereof, polytoluidine and derivatives thereof can be preferably used.
[0066]
Hole transport materials include Tris (4-bromophenyl) for controlling the dopant concentration level as described in Nature, Vol. 395, (1998, 8 Oct.), pages 583-585. Li [(CF to add compounds containing cation radicals such as aminium hexachloroantimonate or to control the potential of oxide semiconductor surfaces (space charge layer compensation)₃SO₂)₂A salt such as N] may be added.
[0067]
(B) Inorganic hole transport material
A p-type inorganic compound semiconductor can be used as the inorganic hole transport material. The p-type inorganic compound semiconductor for this purpose preferably has a band gap of 2 eV or more, and more preferably 2.5 eV or more. Also, the ionization potential of the p-type inorganic compound semiconductor needs to be smaller than the ionization potential of the dye-adsorbing electrode from the condition that the holes of the dye can be reduced. Although the preferable range of the ionization potential of the p-type inorganic compound semiconductor varies depending on the dye used, it is generally preferably 4.5 eV to 5.5 eV, and more preferably 4.7 eV to 5.3 eV. Preferred p-type inorganic compound semiconductors are compound semiconductors containing monovalent copper. Examples of compound semiconductors containing monovalent copper include CuI, CuSCN, and CuInSe.₂, Cu (In, Ga) Se₂, CuGaSe₂, Cu₂O, CuS, CuGaS₂, CuInS₂, CuAlSe₂Etc. Among these, CuI and CuSCN are preferable, and CuI is most preferable. Other p-type inorganic compound semiconductors include GaP, NiO, CoO, FeO, and Bi.₂O_Three, MoO₂, Cr₂O_ThreeEtc. can be used.
[0068]
(D) Counter electrode
Similar to the conductive support described above, the counter electrode may have a single-layer structure of a counter electrode conductive layer made of a conductive material, or may be composed of a counter electrode conductive layer and a support substrate. As a conductive material used for the counter electrode conductive layer, metal (for example, platinum, gold, silver, copper, aluminum, magnesium, indium, etc.), carbon, or conductive metal oxide (indium-tin composite oxide, fluorine-doped tin oxide, Etc.). Among these, platinum, gold, silver, copper, aluminum, and magnesium can be preferably used as the counter electrode layer. An example of a preferable supporting substrate for the counter electrode is glass or plastic, and the above-described conductive agent is applied or vapor-deposited on the glass or plastic. The thickness of the counter electrode conductive layer is not particularly limited, but is preferably 3 nm to 10 μm. The lower the surface resistance of the counter electrode layer, the better. The range of the surface resistance is preferably 50Ω / □ or less, more preferably 20Ω / □ or less.
[0069]
Since light may be irradiated from either or both of the conductive support and the counter electrode, in order for light to reach the photosensitive layer, it is sufficient that at least one of the conductive support and the counter electrode is substantially transparent. . From the viewpoint of improving the power generation efficiency, it is preferable to make the conductive support transparent so that light is incident from the conductive support side. In this case, the counter electrode preferably has a property of reflecting light. As such a counter electrode, glass or plastic on which a metal or a conductive oxide is deposited, or a metal thin film can be used.
[0070]
The counter electrode may be formed by directly applying, plating or vapor-depositing (PVD, CVD) a conductive material on the charge transport layer, or attaching the conductive layer side of the substrate having the conductive layer. Further, as in the case of the conductive support, it is preferable to use a metal lead for the purpose of reducing the resistance of the counter electrode, particularly when the counter electrode is transparent. The preferable metal lead material and installation method, the reduction in the amount of incident light due to the metal lead installation, and the like are the same as those for the conductive support.
[0071]
(E) Other layers
In order to prevent a short circuit between the counter electrode and the conductive support, it is preferable to coat a dense semiconductor thin film layer as an undercoat layer between the conductive support and the photosensitive layer in advance. This is particularly effective when a hole transport material is used. Preferred as an undercoat layer is TiO₂, SnO₂, Fe₂O_Three, WO_Three, ZnO, Nb₂O_FiveAnd more preferably TiO₂It is. The undercoat layer can be applied by, for example, a sputtering method in addition to the spray pyrolysis method described in Electrochim. Acta 40, 643-652 (1995). The preferred thickness of the undercoat layer is 5 to 1000 nm, and more preferably 10 to 500 nm.
Further, a functional layer such as a protective layer or an antireflection layer may be provided on the outer surface of one or both of the conductive support and the counter electrode acting as an electrode, between the conductive layer and the substrate, or in the middle of the substrate. For forming these functional layers, a coating method, a vapor deposition method, a bonding method, or the like can be used depending on the material.
[0072]
(F) Specific example of internal structure of photoelectric conversion element
As described above, the internal structure of the photoelectric conversion element can take various forms depending on the purpose. If roughly divided into two, a structure that allows light to enter from both sides and a structure that allows only one side are possible. 2 to 9 illustrate some of the internal structures of photoelectric conversion elements that can be preferably applied to the present invention as partial cross-sectional views.
In the embodiment shown in FIG. 2, the photosensitive layer 20 including the electrodeposition layer and the charge transport layer 30 are interposed between the transparent conductive layer 10a and the transparent counter electrode conductive layer 40a. It has an incident structure. In the embodiment shown in FIG. 3, the metal lead 11 is partially provided on the transparent substrate 50a, the transparent conductive layer 10a is further provided, and the undercoat layer 60, the photosensitive layer 20, the charge transport layer 30 and the counter electrode conductive layer 40 are arranged in this order. Further, a support substrate 50 is disposed, and light is incident from the conductive layer side. The embodiment shown in FIG. 4 further includes a conductive layer 10 on a support substrate 50, a photosensitive layer 20 provided via an undercoat layer 60, a charge transport layer 30 and a transparent counter electrode conductive layer 40a, A transparent substrate 50a provided with a metal lead 11 is arranged with the metal lead 11 side inward, and light is incident from the counter electrode side. In the embodiment shown in FIG. 5, an undercoat layer 60, a photosensitive layer 20, and a charge transport layer are provided between a pair of metal leads 11 provided on a transparent substrate 50a and further provided with a transparent conductive layer 10a (or 40a). 30 is interposed, and light is incident from both sides. In the embodiment shown in FIG. 6, a transparent conductive layer 10a, an undercoat layer 60, a photosensitive layer 20, a charge transport layer 30 and a counter electrode conductive layer 40 are provided on a transparent substrate 50a, and a support substrate 50 is disposed thereon. In this structure, light enters from the conductive layer side. In the embodiment shown in FIG. 7, the conductive layer 10 is provided on the support substrate 50, the photosensitive layer 20 is provided through the undercoat layer 60, the charge transport layer 30 and the transparent counter electrode conductive layer 40a are provided, and the transparent layer is provided thereon. The substrate 50a is disposed, and light is incident from the counter electrode side. In the embodiment shown in FIG. 8, the transparent conductive layer 10a is provided on the transparent substrate 50a, the photosensitive layer 20 is provided via the undercoat layer 60, and the charge transport layer 30 and the transparent counter electrode conductive layer 40a are provided thereon. A transparent substrate 50a is disposed, and light is incident from both sides. In the embodiment shown in FIG. 9, the conductive layer 10 is provided on the support substrate 50, the photosensitive layer 20 is provided via the undercoat layer 60, and the solid charge transport layer 30 is further provided. Alternatively, it has a metal lead 11 and has a structure in which light enters from the counter electrode side.
[0073]
[2] Photocell
The photovoltaic cell of the present invention is one in which the photoelectric conversion element is made to work with an external load.
Of the photovoltaic cells, the case where the charge transport material is mainly composed of an ion transport material is particularly called a photoelectrochemical cell, and the case where the main purpose is power generation by sunlight is called a solar cell. In order to prevent deterioration of components and volatilization of the contents of the photovoltaic cell, it is preferable to seal the side surface with a polymer or an adhesive. The external circuit itself connected to the conductive support and the counter electrode via a lead may be a known one. When the photoelectric conversion element of the present invention is applied to a solar cell, the structure inside the cell is basically the same as the structure of the photoelectric conversion element described above. Moreover, the dye-sensitized solar cell of the present invention can basically have the same module structure as a conventional solar cell module. The solar cell module generally has a structure in which cells are formed on a support substrate such as metal or ceramic, and the cell is covered with a filling resin or protective glass, and light is taken in from the opposite side of the support substrate. It is also possible to use a transparent material such as tempered glass for the support substrate, configure a cell thereon, and take in light from the transparent support substrate side. Specifically, a module structure called a super straight type, a substrate type, a potting type, a substrate integrated module structure used in an amorphous silicon solar cell, and the like are known, and the dye-sensitized solar cell of the present invention is also used. These module structures can be appropriately selected depending on the place of use and the environment. Specifically, the structure and aspect described in Japanese Patent Application No. 11-8457 are preferable.
[0074]
[Example 1]
Hereinafter, the present invention will be specifically described by way of examples.
In this example, a transparent sheet type photovoltaic cell having the layer structure of FIG. 4 was assembled by the following procedure.
1. Production of transparent conductive support
A 1.9mm-thick alkali-free glass substrate is uniformly coated with fluorine-doped tin dioxide by CVD, with a thickness of 600nm, surface resistance of about 15Ω / □, and light transmittance (500nm) of 85%. A transparent conductive support having a conductive tin dioxide film coated on one side was formed.
[0075]
2. Preparation of semiconductor fine particles
Five types of particle samples of semiconductor fine particles A to E were prepared as follows.
(i) Particle A
C. J. Barbe et al. Am. Ceramic Soc. In accordance with the production method described in the 80th volume, page 3157, titanium tetraisopropoxide was used as the titanium raw material, the temperature of the polymerization reaction in the autoclave was set to 230 ° C., and the anatase type dioxide having a titanium dioxide concentration of 11% by weight. A titanium dispersion was synthesized. The primary particle size of the obtained titanium dioxide particles was 10 to 30 nm. The obtained dispersion was applied to an ultracentrifuge to separate the particles, and the aggregate was pulverized in an agate mortar to obtain a powder.
(ii) Particle B
P-25 manufactured by Nippon Aerosil Co., Ltd. was used. Primary particle size 20nm made by firing method in gas phase, specific surface area 50m determined by BET method²/ g, titanium oxide with anatase content of 77% (TiO₂) Particles.
[0076]
(iii) Particle C
Anatase-type titanium oxide (TiO) manufactured by Aldrich₂)It was used. High whiteness particles having a particle size distribution of 0.1 to 3 μm and anatase content of 99%.
(iv) Particle D
Average particle size 35 μm (by BET method), specific surface area determined by BET method 30 m²/ g, zinc oxide (ZnO) particles synthesized by a vapor phase method comprising hexagonal polyhedrons.
(V) Particle E
Average particle size 15 μm (by BET method), specific surface area determined by BET method 70 m²  / g., tetragonal tin oxide (SnO) synthesized by the vapor phase method₂) Particles.
[0077]
3. Fabrication of semiconductor fine particle layer (electrodeposition)
The five types of fine particles obtained in 2 above were dispersed in a dry mixed solvent of acetonitrile and tert-butanol (1: 1) at an addition amount of 0.035 g / mL to obtain a white dispersion. Originally, the mixture was stirred with ultrasonic waves for 5 minutes. The temperature rise due to ultrasonic stirring was small and thus was not particularly controlled. Two sheets of the above tin oxide transparent conductive support were prepared as an electrodeposition substrate electrode and an electrodeposition counter electrode, and both were made to face the conductive layer side using a 0.3 mm thick Teflon film frame. The semiconductor fine particle dispersion was poured into the gap between the two electrodes and allowed to stand, and the following voltage was applied between the electrodes using a DC power source to perform electrodeposition.
[0078]

[0079]
The obtained electrodeposition layer was dried at room temperature for 30 minutes and then heated in dry air at 120 ° C. The yield by electrodeposition (electrodeposited particles / total particles) was approximately 100% for particles A, B, and C, but particles D and E were unstable in the range of 70 to 90%.
The particle loading of the electrodeposition layer thus obtained was as follows: Substrate A: 9.9 g / m for Substrate A to E carrying Particles A to E, respectively.²Substrate B: 10.0 g / m²Substrate C: 9.8 g / m²Substrate D: 8.0 g / m²Substrate E: 8.2 g / m²It became. The average film thickness of the electrodeposition layer was as follows: substrate A: 7 μm, substrate B: 8 μm, substrate C: 9 μm, substrate D: 6 μm, substrate E: 5.5 μm.
A part of the electrodeposition substrate was further exposed to UV light from a 100 W mercury lamp ultraviolet light source at 150 ° C. for 1 hour for post-treatment.
[0080]
4). Preparation of dye adsorption solution
As a sensitizing dye having absorption up to 750 nm on the long wavelength side and having an absorption peak in the blue to green region, the Ru complex dye (Dye R-1) of the above-mentioned specific example was dried with acetonitrile: t-butanol: ethanol (2 : 3: 1 concentration in mixed solvent of 1: 1)^-FourDissolved in mol / liter. As an additive to this dye solution, p-C₉H₁₉-C₆H_Four-O- (CH₂CH₂-O)_Three-(CH₂) 4-SO_ThreeAn organic sulfonic acid derivative having a Na structure was dissolved to a concentration of 0.025 mol / liter to prepare a dye adsorption solution.
[0081]
5. Dye adsorption
The semiconductor fine particle electrodeposition substrates A to E were immersed in the adsorption dye solution and allowed to stand at 40 ° C. for 3 hours with stirring. After the dye was adsorbed on the fine electrodeposition layer in this way, the electrode was washed with acetonitrile to prepare a dye-sensitized electrode used for the photosensitive layer.
[0082]
6). Production of photoelectrochemical cell
The electrodeposition layer of the dye-sensitized semiconductor electrode is scraped off leaving a circular portion having a diameter of about 1.1 cm, and a light receiving area of 1.0 cm²A circular light-receiving layer having a diameter of about 1.1 cm was formed. A counter-plated platinum-deposited glass substrate is superimposed on this electrode by inserting a thermo-compressible polyethylene film frame spacer (thickness 20 μm), and the spacer portion is heated to 120 ° C. to pressure-bond both substrates. . Furthermore, the edge part of the cell was sealed with an epoxy resin adhesive. Room temperature molten salt composed of Y6-2 / Y9-1 / iodine = 15: 35: 1 (weight ratio) as electrolyte through a small hole for electrolyte injection provided in the corner of the counter electrode substrate in advance The space between the electrodes was soaked from the small holes of the substrate using capillary action. The above cell assembling step and electrolyte solution injection step were all performed in the above-described dry air at a dew point of −60 ° C. After injecting the molten salt, the cell was sucked for several hours under vacuum to deaerate the inside of the cell, such as a porous semiconductor electrode and molten salt, and finally the small holes were sealed with low-melting glass.
In the same manner, the transparent photoelectric conversion element of the present invention is produced using a long-wavelength dye R-10 having absorption in the visible region up to 900 nm as the sensitizing dye instead of R-1 used in the above examples. did.
[0083]
7). Measurement of photoelectric conversion efficiency
A 500 W xenon lamp (USHIO) equipped with a correction filter for sunlight simulation (AM1.5 direct manufactured by Oriel) has an incident light intensity of 100 mW / cm with respect to the photoelectric conversion element.²The simulated sunlight was irradiated from the side of the transparent electrode carrying the semiconductor fine particle electrodeposition layer. The element was fixed in close contact on the stage of a thermostat, and the temperature of the element during irradiation was controlled at 50 ° C.
Using a current-voltage measuring device (Keutley source measure unit 238 type), the DC voltage applied to the element is scanned at a constant speed of 10 mV / second, and the photocurrent output from the element is measured, so that photocurrent-voltage Characteristics were measured. Table 1 shows the photocurrent density (Jsc), open circuit electromotive force (Voc), and energy conversion efficiency (η) of the above-described various elements, together with the contents of the cell components (semiconductor fine particles, sensitizing dyes). It was described in.
In the table, as a comparative experiment, the results of devices manufactured by changing the electrodeposition conditions (electrodeposition voltage, heat treatment after electrodeposition) are also shown.
[0084]
[Table 1]

[0085]
[Table 2]

[0086]
From the results in Table 1, the following is clear.
1) Using the electrodeposited layer of semiconductor fine particles according to the production method of the present invention, energy conversion efficiency suitable for practical use as a solar cell can be obtained without firing the electrode at high temperature.
2) As a condition of the electric field used for electrodeposition, electrodeposition using a low electric field having an absolute value of 50 V / cm or less reduces the amount of electrodeposition on the substrate, resulting in a decrease in performance (particularly Jsc). There is a trend. In addition, in electrodeposition using a high electric field having an absolute value of 300 V / cm or more, although the amount of electrodeposition did not decrease, there was a tendency for performance to decrease. The reason for this is unknown, but it is presumed that the substrate resistance increased due to the electrochemical deterioration of the conductive film of the substrate, and the fill factor (FF) was affected.
3) When the electrodeposition film is subjected to heat treatment, performance is improved, and when the heat treatment and UV light irradiation treatment are performed simultaneously, further performance improvement is observed.
[0087]
[Example 2]
A dye is produced by the same steps and operations as in Example 1 except that the transparent conductive glass support and the platinum-deposited glass (counter electrode) used in Example 1 are used instead of the following plastic transparent conductive sheets. A plastic sheet-type photoelectric conversion cell in which both the sensitized semiconductor working electrode and the counter electrode are made of a plastic substrate was produced.
1. Transparent conductive plastic sheet for working electrode
A flexible substrate made by uniformly coating a thin film of conductive indium tin oxide (ITO) with a thickness of 200 nm on one side of a 0.4 mm thick polyester sheet, with a surface resistance of about 20Ω / □, light transmission A transparent conductive plastic sheet having a rate (500 nm) of 88%.
2. Conductive plastic sheet for the counter electrode
A conductive plastic sheet having a surface resistance of about 5 Ω / □, which is obtained by uniformly coating a platinum film with a thickness of 300 nm on one surface of a polyimide Kapton film having a thickness of 0.4 mm by vacuum sputtering.
[0088]
Table 2 shows the configuration and performance of photoelectrochemical cells assembled using these plastic electrode substrates. Compared to the results using the glass substrate shown in Table 1, as a result of the lower FF due to the higher surface resistance of the ITO / polyester substrate (lower conductivity), the cell using the glass substrate However, it is understood that the photoelectric conversion performance at a practical level is obtained. Moreover, especially these cells have the merit as a flexible cell which provided the softness | flexibility by not using glass.
[0089]
[Table 3]

[0090]
As described above, by using the electrodeposited layer of semiconductor fine particles of the present invention as a photosensitive layer, a dye-sensitized photoelectric conversion element can be produced by an inexpensive means not including a baking step, and also as a solar cell. An element having useful performance can be provided using various substrates including a plastic sheet.
[0091]
【The invention's effect】
According to the present invention, a dye-sensitized photoelectric conversion element and a photoelectrochemical cell excellent in energy conversion efficiency and cost performance can be obtained.
[Brief description of the drawings]
FIG. 1 is a partial cross-sectional view showing the structure of a preferred photoelectric conversion element of the present invention.
FIG. 2 is a partial cross-sectional view illustrating a structure of a photoelectric conversion element according to another embodiment of the present invention.
FIG. 3 is a partial cross-sectional view showing the structure of a photoelectric conversion element according to still another embodiment of the present invention.
FIG. 4 is a partial cross-sectional view showing the structure of a photoelectric conversion element according to still another embodiment of the present invention.
FIG. 5 is a partial cross-sectional view showing the structure of a photoelectric conversion element according to still another embodiment of the present invention.
FIG. 6 is a partial cross-sectional view showing a structure of a photoelectric conversion element according to still another embodiment of the present invention.
FIG. 7 is a partial cross-sectional view showing the structure of a photoelectric conversion element according to still another embodiment of the present invention.
FIG. 8 is a partial cross-sectional view showing the structure of a photoelectric conversion element according to still another embodiment of the present invention.
FIG. 9 is a partial cross-sectional view showing the structure of a photoelectric conversion element according to still another embodiment of the present invention.
[Explanation of symbols]
10 ... conductive layer
10a ・ ・ ・ Transparent conductive layer
11 ... Metal lead
20 ... Photosensitive layer
21 ... Semiconductor fine particles
22 ... Dye
23 ... Charge transport material
30 ... Charge transport layer
40 ... Counterelectrode conductive layer
40a ・ ・ ・ Transparent counter conductive layer
50 ... Board
50a ・ ・ ・ Transparent substrate
60 ... Undercoat layer

Claims (10)

A method for producing a photoelectric conversion element having a laminated structure including a conductive support having a conductive layer, a semiconductor fine particle layer, a charge transport layer, and a counter electrode, wherein the semiconductor fine particles are attached to the conductive layer of the conductive support by electrophoresis A step of forming the semiconductor fine particle layer by heating, and a step of heating the formed semiconductor fine particle layer at 100 ° C. to 250 ° C. under irradiation of light absorbed by the semiconductor fine particles. Device manufacturing method.   The method for producing a photoelectric conversion element according to claim 1, wherein the electrophoresis is performed using a semiconductor fine particle dispersion containing no electrolyte.   The method for producing a photoelectric conversion element according to claim 1, wherein the electrophoresis is performed in a direct current electric field, and the strength of the electric field is 50 V / cm or more and 300 V / cm or less. The conductive support of the electrically conductive layer, a method for manufacturing a photoelectric conversion element according to any one of claims 1 to 3, characterized in that it comprises a tin oxide. The semiconductor fine particles, titanium oxide, zinc oxide, tin oxide, tungsten oxide, according to claim 1-4, wherein the niobium oxide and a semiconductor selected from combinations of two or more of the complex The manufacturing method of the photoelectric conversion element in any one. The semiconductor fine particle layer, the manufacturing method of the photoelectric conversion device according to any one of claims 1 to 5, characterized in that it is sensitized with dyes. The method of producing a photoelectric conversion element according to any one of claims 1 to 6 wherein said charge transfer layer is characterized in that it comprises a molten salt electrolyte. Wherein the conductive support is a method for manufacturing a photoelectric conversion element according to any one of claims 1 to 7, characterized in that a plastic support having a conductive layer. The photoelectric conversion element manufactured by the manufacturing method in any one of Claims 1-8 . A photovoltaic cell using the photoelectric conversion element according to claim 9 .

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