JP2004111276A - Dye sensitizing solar cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dye sensitizing solar cell capable of easily improving thermal resistance, light resistance and chemical stability of dyes and capable of obtaining excellent photoelectric transfer efficiency for a long period of time. <P>SOLUTION: The dye sensitizing solar cell 20 has a semiconductor electrode 2 having a light-receiving face F2, a transparent electrode 1 arranged in adjacency on the light-receiving face F2, and a counter electrode CE, with a structure of the semiconductor electrode and the counter electrode arranged in opposition with an interposition of an electrolyte (an electrolyte solution E). The semiconductor electrode contains dyes, and the electrolyte (the electrolyte solution E) contains a boric compound with a hydrolytic ability for preventing decomposition of the dyes. <P>COPYRIGHT: (C)2004,JPO

Description

【００４３】
ここで、式（１）中、ｎは、１〜３の整数を示し、Ｘは、加水分解能を有する特性基を示し、Ｒ^１は、アルキル基、アルケニル基、アルキニル基、アリル基、アリール基、及び、複素環基からなる群から選択される少なくとも１種の炭化水素基を示す。
【００４４】
なお、本明細書において、「複素環基」とは、ピロール、ピロリン、オキサゾール、イソオキサゾール、チアゾール、イソチアゾール、イミダゾール、イミダゾリン、ピラゾール、トリアゾール、フラザン、テトラゾール、ピラン、チイン、ピリジン、オキサジン、チアジン、ピリタジン、ピリミジン、ピラジン、トリアジン、ベンゾフラン、イソベンゾフラン、ベンゾチオフェン、インドール、イソインドール、ベンゾオキサゾール、ベンゾチアゾール、インダゾール、ベンゾイミダゾール、クロメン、クロマン、キノリン、イソキノリン、シンノリン、フタラジン、キナゾリン、キノキサリン、ジベンゾフラン、カルバゾール、キサンテン、アクリジン、フェナントリジン、フェナントロリン、フェナジン、フェノキサジン、チアントレン、インドリジン、チノリジン、ナフチリジン、プリン、及び、プテリジンからなる群から選択される少なくとも１種を示す。
【００４５】
また、加水分解能を有するホウ素化合物の電解質中での長期にわたる化学的安定及び加水分解反応に対する反応性を充分に確保する観点と、加水分解反応の反応生成物の電池反応に対する阻害性を充分に低減するという観点から、Ｒ^１となるアルキル基は炭素数が１〜２０であることが好ましく、Ｒ^１となるアルケニル基炭素数が２〜２０であることが好ましく、Ｒ^１となるアルキニル基は炭素数が２〜２０であることが好ましい。
【００４６】
また、上記と同様の観点から、式（１）中のＸは、下記一般式（２）〜（５）及びハロゲン原子からなる群より選択される少なくとも１種であることが好ましい。
【００４７】
【化８】

【００４８】
【化９】

【００４９】
【化１０】

【００５０】
【化１１】

【００５１】
ここで、式（２）〜（５）中、Ｒ^１は式（１）中に記載のＲ^１と同義であり、Ｒ^２及びＲ^３は同一であっても異なっていてもよく、それぞれ独立に、水素原子、アルキル基、アルケニル基、アルキニル基、アリル基、アリール基、及び、複素環基からなる群から選択される少なくとも１種を示し、Ｒ^４、Ｒ^５及びＲ^６は同一であっても異なっていてもよく、それぞれ独立に、水素原子、アルキル基、アルケニル基、アルキニル基、アリル基、アリール基、及び、複素環基からなる群から選択される少なくとも１種を示す。
【００５２】
また、加水分解能を有するホウ素化合物の電解質中での長期にわたる化学的安定及び加水分解反応に対する反応性を充分に確保する観点と、加水分解反応の反応生成物の電池反応に対する阻害性を充分に低減するという観点から、Ｒ^２、Ｒ^３、Ｒ^４、Ｒ^５又はＲ^６となるアルキル基は炭素数が１〜２０であることが好ましく、Ｒ^２、Ｒ^３、Ｒ^４、Ｒ^５又はＲ^６となるアルケニル基は炭素数が２〜２０であることが好ましく、Ｒ^２、Ｒ^３、Ｒ^４、Ｒ^５又はＲ^６となるアルキニル基は炭素数が２〜２０であることが好ましい。
【００５３】
更に、色素（金属錯体色素及び有機色素）及び電解液Ｅの酸化分解、光分解及び熱分解の進行をより確実に防止する観点から、式（１）〜式（４）中のＲ^１を構成する少なくとも１つの水素原子が、スルホ基、スルフィノ基、スルフェノ基（−ＳＯ−）、オキシカルボニル基（−ＣＯ−Ｏ−）、ハロホルミル基、カルバモイル基、ヒドラジノカルボニル基（−ＣＯ−ＮＨ−ＮＨ_２）、アミジノ基、シアノ基、イソシアノ基、シアナト基、イソシアナト基、チオシアナト基、イソチオシアナト基、ホルミル基、オキソ基、チオホルミル基、チオキソ基、メルカプト基、アミノ基、イミノ基、ヒドラジノ基、アリロキシ基（−Ｏ−Ｒ_Ａ）、スルフィド基（−Ｓ−Ｒ^４）、ニトロ基、シリル基及びハロゲン原子からなる群より選択される少なくとも１種の置換基により更に置換されていてもよい。なお、上記の「Ｒ^４」は炭素数１〜５０のアルキル基又は芳香族置換基を示す。また、上記の「Ｒ_Ａ」は芳香族置換基を示す。
【００５４】
また、上述したように色素（金属錯体色素及び有機色素）及び電解液Ｅの酸化分解、光分解及び熱分解をより十分に防止する観点から、式（４）中のＲ^２及びＲ^３のうちの少なくとも一方が、アルキル基、アルケニル基、アルキニル基、アリル基、アリール基、及び、複素環基からなる群から選択される少なくとも１種であることが好ましい。
【００５５】
更に、この場合には、式（４）中のＲ^２及びＲ^３のうちの少なくとも一方を構成する少なくとも１つの水素原子が、スルホ基、スルフィノ基、スルフェノ基（−ＳＯ−）、オキシカルボニル基（−ＣＯ−Ｏ−）、ハロホルミル基、カルバモイル基、ヒドラジノカルボニル基（−ＣＯ−ＮＨ−ＮＨ_２）、アミジノ基、シアノ基、イソシアノ基、シアナト基、イソシアナト基、チオシアナト基、イソチオシアナト基、ホルミル基、オキソ基、チオホルミル基、チオキソ基、メルカプト基、アミノ基、イミノ基、ヒドラジノ基、アリロキシ基（−Ｏ−Ｒ_Ａ）、スルフィド基（−Ｓ−Ｒ^４）、ニトロ基、シリル基及びハロゲン原子からなる群より選択される少なくとも１種の置換基により更に置換されていてもよい。なお、上記の「Ｒ^４」は炭素数１〜５０のアルキル基又は芳香族置換基を示す。また、上記の「Ｒ_Ａ」は芳香族置換基を示す。
【００５６】
また、上述したように色素（金属錯体色素及び有機色素）及び電解液Ｅの酸化分解、光分解及び熱分解をより十分に防止する観点から、式（５）中のＲ^４、Ｒ^５及びＲ^６のうちの少なくとも１つが、アルキル基、アルケニル基、アルキニル基、アリル基、アリール基、及び、複素環基からなる群から選択される少なくとも１種であることが好ましい。
【００５７】
更に、この場合には、式（５）中のＲ^４、Ｒ^５及びＲ^６のうちの少なくとも１つを構成する少なくとも１つの水素原子が、スルホ基、スルフィノ基、スルフェノ基（−ＳＯ−）、オキシカルボニル基（−ＣＯ−Ｏ−）、ハロホルミル基、カルバモイル基、ヒドラジノカルボニル基（−ＣＯ−ＮＨ−ＮＨ_２）、アミジノ基、シアノ基、イソシアノ基、シアナト基、イソシアナト基、チオシアナト基、イソチオシアナト基、ホルミル基、オキソ基、チオホルミル基、チオキソ基、メルカプト基、アミノ基、イミノ基、ヒドラジノ基、アリロキシ基（−Ｏ−Ｒ_Ａ）、スルフィド基（−Ｓ−Ｒ^４）、ニトロ基、シリル基及びハロゲン原子からなる群より選択される少なくとも１種の置換基により更に置換されていてもよい。なお、上記の「Ｒ^４」は炭素数１〜５０のアルキル基又は芳香族置換基を示す。また、上記の「Ｒ_Ａ」は芳香族置換基を示す。
【００５８】
上述した式（１）式で表される加水分解能を有するホウ素化合物の好ましい具体例としては、例えば、下記化学式（Ａ１）〜（Ａ４）の化合物が挙げられる。
【００５９】
【化１２】

【００６０】
【化１３】

【００６１】
【化１４】

【００６２】
【化１５】

【００６３】
また、加水分解能を有するホウ素化合物としては、式（１）で表される化合物が２以上結合した構造を有するものであってもよい。ここで、「式（１）で表される化合物が２以上結合した構造」とは以下の構造を示す。すなわち、２以上の式（１）で表される化合物が、それぞれの特性基Ｘ同士の間で共有結合を形成した構造、それぞれの炭化水素基Ｒ^１同士の間で共有結合を形成した構造、又は、一方の特性基Ｘと他方の炭化水素基Ｒ^１との間で共有結合を形成した構造を示す。
【００６４】
例えば、２つの式（１）で表される化合物が、それぞれの特性基Ｘ同士の間で共有結合を形成した構造を有する化合物としては、下記式（Ｂ１）で表される化合物が挙げられる。
【００６５】
【化１６】

【００６６】
また、加水分解能を有するホウ素化合物は、下記一般式（７）で表される化合物であってもよい。
【００６７】
【化１７】

【００６８】
ここで、式（７）中、Ｒ^７、Ｒ^８、Ｒ^９及びＲ^１０はそれぞれ式（１）中のＲ^１と同義の基であるか、又は、Ｒ^７、Ｒ^８、Ｒ^９及びＲ^１０のうちの少なくとも１つが、式（１）中のＸと同義の基でありかつ該Ｘと同義の基以外の基は式（１）中のＲ^１と同義の基である。なお、加水分解能を有するホウ素化合物としては、式（７）で表される化合物の他に、式（７）中の酸素原子をＳに置換した化合物も挙げられる。
【００６９】
例えば、式（７）で表される化合物としては、例えば、下記式（Ｃ１）で表される化合物が挙げられる。
【００７０】
【化１８】

【００７１】
また、加水分解能を有するホウ素化合物は、下記一般式（８）で表される化合物であってもよい。
【００７２】
【化１９】

【００７３】
ここで、式（７）中、Ｒ^１１、Ｒ^１２、Ｒ^１３及びＲ^１４はＲ^１１、Ｒ^１２、Ｒ^１３及びＲ^１４のうちの少なくとも１つが、式（１）中のＸと同義の基でありかつ該Ｘと同義の基以外の基は式（１）中のＲ^１と同義の基である。
【００７４】
例えば、式（８）で表される化合物としては、例えば、下記式（Ｄ１）で表される化合物が挙げられる。
【００７５】
【化２０】

【００７６】
更に、加水分解能を有するホウ素化合物は、２以上の下記一般式（６）で表される化合物を分子間脱水反応させることにより得られる反応生成物であってもよい。ここで、下記式（６）中、ｍは、１〜３の整数を示し、Ｒ^１は、式（１）中のＲ^１と同義である。
【化２１】

【００７７】
この場合にも、加水分解能を有するホウ素化合物の電解質中での長期にわたる化学的安定及び加水分解反応に対する反応性を充分に確保する観点と、加水分解反応の反応生成物の電池反応に対する阻害性を充分に低減するという観点から、Ｒ^１となるアルキル基は炭素数が１〜２０であることが好ましく、Ｒ^１となるアルケニル基炭素数が２〜２０であることが好ましく、Ｒ^１となるアルキニル基は炭素数が２〜２０であることが好ましい。
【００７８】
更に、色素（金属錯体色素及び有機色素）及び電解液Ｅの酸化分解、光分解及び熱分解の進行をより確実に防止する観点から、式（６）中のＲ^１を構成する少なくとも１つの水素原子が、スルホ基、スルフィノ基、スルフェノ基（−ＳＯ−）、オキシカルボニル基（−ＣＯ−Ｏ−）、ハロホルミル基、カルバモイル基、ヒドラジノカルボニル基（−ＣＯ−ＮＨ−ＮＨ_２）、アミジノ基、シアノ基、イソシアノ基、シアナト基、イソシアナト基、チオシアナト基、イソチオシアナト基、ホルミル基、オキソ基、チオホルミル基、チオキソ基、メルカプト基、アミノ基、イミノ基、ヒドラジノ基、アリロキシ基（−Ｏ−Ｒ_Ａ）、スルフィド基（−Ｓ−Ｒ^４）、ニトロ基、シリル基及びハロゲン原子からなる群より選択される少なくとも１種の置換基により更に置換されていてもよい。なお、上記の「Ｒ^４」は炭素数１〜５０のアルキル基又は芳香族置換基を示す。また、上記の「Ｒ_Ａ」は芳香族置換基を示す。
【００７９】
例えば、式（６）で表される化合物としては、例えば、下記式（Ｇ１）で表される化合物が挙げられる。また、下記式（Ｇ１）で表される化合物の分子間脱水反応により得られる反応生成物としては、例えば、下記式（Ｇ２）及び（Ｇ３）が挙げられる。
【００８０】
【化２２】

【００８１】
【化２３】

【００８２】
【化２４】

【００８３】
更に、加水分解能を有するホウ素化合物は、２以上の下記一般式（９）で表される化合物を縮合反応させることにより得られる反応生成物であってもよい。ここで、下記式（９）中、ｍは、１〜３の整数を示し、Ｒ^１は、式（１）中のＲ^１と同義である。この場合、副生成物としては、例えば、Ｈ_２Ｓが生成する。
【００８４】
【化２５】

【００８５】
また、加水分解能を有するホウ素化合物は、２以上の下記一般式（１０）で表される化合物を分子間脱水反応させることにより得られる反応生成物であってもよい。ここで、下記式（１０）中、ｍは、１〜３の整数を示し、Ｒ^１は、式（１）中のＲ^１と同義である。この場合、副生成物としては、例えば、ＮＨ_３が生成する。
【００８６】
【化２６】

【００８７】
更に、加水分解能を有するホウ素化合物は、２以上の下記一般式（１１）で表される化合物を分子間脱水反応させることにより得られる反応生成物であってもよい。ここで、下記式（１１）中、ｍは、１〜３の整数を示し、Ｒ^１は、式（１）中のＲ^１と同義である。この場合、副生成物としては、例えば、Ｒ^１ _３Ｓｉ（ＯＨ）が生成する。
【００８８】
【化２７】

【００８９】
なお、以上説明した全ての加水分解能を有するホウ素化合物は、異なる構造を有するものを任意に組み合せて同時に使用してもよい。
【００９０】
また、電解液Ｅ中の加水分解能を有するホウ素化合物の濃度は、１ｍｍｏｌ／Ｌ〜１ｍｏｌ／Ｌであることが好ましい。加水分解能を有するホウ素化合物の濃度が１ｍｍｏｌ／Ｌ未満であると、色素（金属錯体色素及び有機色素）の分解防止の効果を充分に得ることができなくなる傾向が大きくなる。また加水分解能を有するホウ素化合物の濃度が１ｍｏｌ／Ｌを超えると、電解液Ｅ中に溶解しにくくなる傾向が大きくなる。
【００９１】
また、電解液Ｅには、紫外線吸収剤を更に含有させていてもよい。紫外線吸収剤を電解質Ｅ中に含有させることにより、光電極１０に照射される光のうち、色素（金属錯体色素及び有機色素）の光増感機能の劣化に大きな影響を与える紫外線を選択的に吸収することができ、電解質中において色素（金属錯体色素及び有機色素）をより安定化した状態で保持することができるようになる。
【００９２】
また、スペーサＳの構成材料は特に限定されるものではなく、例えば、シリカビーズ等を用いることができる。
【００９３】
また、電解液Ｅを密封する目的で光電極１０、対極ＣＥ及びスペーサＳを一体化するために使用する封止材としては、電解液Ｅの成分ができる限り外部に漏洩しないように封止できるものであればよく、特に制限されないが、例えば、エポキシ樹脂、シリコーン樹脂、エチレン／メタクリル酸共重合体，表面処理ポリエチレンからなる熱可塑性樹脂などを用いることができる。
【００９４】
次に、図１に示した色素増感型太陽電池２０の製造方法の一例について説明する。
【００９５】
透明電極１を製造する場合は、ガラス基板等の基板４上に先に述べたフッ素ドープＳｎＯ_２等の透明導電膜３をスプレーコートする等の公知の薄膜製造技術を用いて形成することができる。例えば、この他にも、真空蒸着法、スパッタリング法、ＣＶＤ法及びゾルゲル法の公知の薄膜製造技術を用いて形成することができる。
【００９６】
透明電極１の透明導電膜３上に半導体電極２を形成する方法としては、例えば、以下の方法がある。すなわち、先ず、所定の大きさ（例えば粒子径が１０〜３０ｎｍ程度）を有する酸化物半導体粒子を分散させた分散液を調製する。この分散液の溶媒は水、有機溶媒、または両者の混合溶媒など酸化物半導体粒子を分散できるものなら特に限定されない。また、分散液中には必要に応じて界面活性剤、粘度調節剤を加えてもよい。
【００９７】
次に、分散液を透明電極１の透明導電膜３上に塗布し、次いで乾燥する。このときの塗布方法としてはバーコーター法、印刷法などを用いることができる。そして、乾燥した後、空気中、不活性ガス或いは窒素中で加熱、焼成して半導体電極２（多孔質半導体膜）を形成する。
【００９８】
次に、半導体電極２中に浸着法等の公知の技術により色素を含有させる。増感色素は半導体電極２に付着（化学吸着、物理吸着または堆積など）させることにより含有させる。この付着方法は、例えば色素を含む溶液中に半導体電極２を浸漬するなどの方法を用いることができる。この際、溶液を加熱し還流させるなどして色素の吸着、堆積を促進することができる。なお、このとき、色素の他に必要に応じて、銀等の金属やアルミナ等の金属酸化物を半導体電極２中に含有させてもよい。
【００９９】
また、半導体電極２内に含まれる光電変換反応を阻害する不純物を除去する表面酸化処理を、各層それぞれの形成時毎、或いは、各層全てを形成した時などに公知の方法により適宜施してもよい。
【０１００】
また、透明電極１の透明導電膜３上に半導体電極２を形成する他の方法としては、以下の方法がある。すなわち、透明電極１の透明導電膜３上にＴｉＯ_２等の半導体を膜状に蒸着させる方法を用いてもよい。透明導電膜３上に半導体を膜状に蒸着させる方法としては公知の薄膜製造技術を用いることができる。例えば、電子ビーム蒸着、抵抗加熱蒸着、スパッタ蒸着、クラスタイオンビーム蒸着等の物理蒸着法を用いてもよく、酸素等の反応性ガス中で金属等を蒸発させ、反応生成物を透明導電膜３上に堆積させる反応蒸着法を用いてもよい。更に、反応ガスの流れを制御する等してＣＶＤ等の化学蒸着法を用いることもできる。
【０１０１】
このようにして光電極１０を作製した後は、例えば、光電極１０の作製に用いた方法と同様の公知の薄膜製造技術により対極ＣＥを作製し、図１に示すように、光電極１０と、対極ＣＥとをスペーサＳを介して対抗させるように組み上げる。このとき、スペーサＳにより光電極１０と対極ＣＥとの間に形成される空間に、先に述べた成分を含む電解液Ｅを充填し、色素増感型太陽電池２０を完成させる。
【０１０２】
［第２実施形態］
図２は、本発明の色素増感型太陽電池の第２実施形態を示す模式断面図である。以下、図２に示す色素増感型太陽電池３０について説明する。なお、上述の図１に示した色素増感型太陽電池２０に関して説明した要素と同一の要素については同一の符号を付し、重複する説明は省略する。
【０１０３】
図２に示す色素増感型太陽電池３０は、図１に示した光電極１０を使用し、図１に示した対極ＣＥと同様の対極ＣＥを使用している。そして、図１に示した色素増感型太陽電池２０においてはスペーサＳにより光電極１０と対極ＣＥとの間に形成される空間に電解液Ｅを充填したのに比較して、図２に示す色素増感型太陽電池３０においては、光電極１０と対極ＣＥとの間に多孔体層ＰＳを配置している。そして、対極ＣＥの多孔体層ＰＳと反対側の面には透明基板６が配置されている。
【０１０４】
この多孔体層ＰＳは多数の細孔を有した構造を有しており、この多孔体層ＰＳの内部には、図１に示した色素増感型太陽電池２０に使用したものと同様の電解液Ｅが充填されて保持されている。
【０１０５】
また、この電解液Ｅは半導体電極２内や、使用する構成材料（例えば、炭素等の多孔質の導電性膜）によっては対極ＣＥにも保持されている。そして、図２に示す色素増感型太陽電池３０の半導体電極２、多孔体層ＰＳ及び対極ＣＥの側面は、電解液Ｅが、半導体電極２、多孔体層ＰＳ及び対極ＣＥの側面から外部に漏れることを防止するためにシール材５により被覆されている。
【０１０６】
多孔体層ＰＳは、電解液Ｅを保持可能であり、電子伝導性を有さない多孔体であれば特に限定されない。例えば、ルチル型の酸化チタン粒子により形成した多孔体を使用してもよい。また、ルチル型の酸化チタン以外の構成材料としては、ジルコニア、アルミナ、シリカ等が挙げられる。
【０１０７】
また、シール材５としては、例えば、ポリエチレン等の熱可塑性樹脂フィルム、あるいはエポキシ系接着剤を使用することができる。対極ＣＥの側に配置される透明基板６は光電極１０の透明電極１に使用される透明基板４と同様の基板を使用することができる。
【０１０８】
次に、図２に示す色素増感型太陽電池３０の製造方法の一例について説明する。先ず、図１に示した色素増感型太陽電池２０と同様にして光電極１０を作製する。次に、光電極１０の半導体電極２を作製する場合と同様の手順により、光電極１０の半導体電極２の面Ｆ２２上に多孔体層ＰＳを形成する。例えば、ルチル型の酸化チタン等の多孔体層ＰＳの構成材料を含む分散液（スラリー）を調製し、これを半導体電極２の面Ｆ２２上に塗布し乾燥させることにより形成してもよい。
【０１０９】
また、対極ＣＥについても、例えば、炭素等の多孔質の導電性膜を対極ＣＥとする場合には、例えば、カーボンペーストを調製し、これを多孔体層ＰＳの面上に塗布し乾燥させることにより形成してもよい。そして、公知の薄膜製造技術により、対極ＣＥの多孔体層ＰＳの側と反対の側の面上に透明基板６を形成し、半導体電極２、多孔体層ＰＳ及び対極ＣＥの側面をシール材５で被覆して色素増感型太陽電池３０を完成する。
【０１１０】
以上、本発明の好適な実施形態について説明したが、本発明は上記実施形態に限定されるものではない。
【０１１１】
例えば、本発明の色素増感型太陽電池は、例えば、図３に示す色素増感型太陽電池４０のように、複数の電池を併設したモジュールの形態を有していてもよい。図３に示す色素増感型太陽電池４０は、図２に示した色素増感型太陽電池３０を複数個直列に併設する場合の一例を示している。
【０１１２】
図２に示した色素増感型太陽電池３０に比較して、図３に示す色素増感型太陽電池４０は、隣り合う太陽電池の単セルの光電極１０間に設けられるシール材５と一方の単セル（以下、単セルＡという）の光電極１０との間に溝が形成されている。
【０１１３】
この溝は、単セルＡの半導体電極２を、例えばレーザースクライブなどの技術により削りとることにより形成される。この溝のうちのシール材５の近傍部分は、半導体電極２の部分を完全に除去して透明電極１の透明導電膜３の層があらわれる深さまで達している。また、この溝のうちの単セルＡの半導体電極２の近傍部分は、半導体電極２の部分と透明導電膜３の部分を完全に除去して、透明電極１の透明基板４の層があらわれる深さまで達している。
【０１１４】
そして、この溝のうちのシール材５の近傍部分には、隣り合う光電極１０の透明導電膜３及び該透明導電膜３上の半導体電極２の部分同士が電気的に接触しないように、これらの部分の間に単セルＡの多孔体層ＰＳの鍔状に形成された縁部分が透明電極１の透明基板４に接触するようにして挿入されている。
【０１１５】
更に、この溝のうちの単セルＡの半導体電極２の近傍部分、すなわち、単セルＡの多孔体層ＰＳとシール材５との間の部分には、単セルＡの対極ＣＥの鍔状に形成された縁部分が、もう一方の単セルの透明電極１の透明導電膜３に接触するようにして挿入されている。
【０１１６】
【実施例】
以下、実施例及び比較例を挙げて本発明の色素増感型太陽電池について更に詳しく説明するが、本発明はこれらの実施例に何ら限定されるものではない。
【０１１７】
（実施例１）
以下に示す手順により、図１に示した光電極１０と同様の構成を有する光電極を作製し、更に、この光電極を用いた以外は図１に示す色素増感型太陽電池２０と同様の構成を有する色素増感型太陽電池（受光面の面積：１ｃｍ^２）を作製した。
【０１１８】
先ず、オートクレーブの温度を２３０℃とした以外は、Ｊｏｕｒｎａｌ　ｏｆ　ｃｅｒａｍｉｃ　ｓｏｃｉｅｔｙ　（第８０巻、第３１５７〜３１７１頁、１９８７年）に記載のバルベらの方法に従いアセチルアセトン、イオン交換水、界面活性剤（Ａｌｄｒｉｃｈ社製、商品名；「ｔｒｉｔｏｎＸ」）からなる液にＴｉＯ_２粒子（Ｄｅｇｕｓｓａ社製、商品名；「Ｐ２５」）を分散した半導体電極形成用のスラリー（ＴｉＯ_２粒子の含有量；１１質量％、ＴｉＯ_２粒子の平均粒子径：約１０ｎｍ、「スラリー１」とする）を調製した。
【０１１９】
次に、スラリー１中に増粘剤としてポリエチレングリコール（和光純薬社製、数平均分子量；２０００）を添加し混合することにより、半導体電極形成用のペースト（以下、ペースト１という）を調製した。なお、ペースト１中のＴｉＯ_２粒子とポリエチレングリコールとの質量比はＴｉＯ_２粒子：ポリエチレングリコール＝１０：３となるように調節した。
【０１２０】
一方、ガラス基板４（透明導電性ガラス）上にフッ素ドープされたＳｎＯ_２導電膜３（膜厚；６００ｎｍ）を形成した透明電極１（日本板ガラス社製、表面抵抗；約１０Ω／ｃｍ^２、厚さ；１ｍｍ）を準備した。そして、このＳｎＯ_２導電膜３上に、上述のペースト１をドクターブレードを用いて１００μｍの厚さとなるまで塗布し、次いで温度を２５℃に保持して３０分間乾燥させた。
【０１２１】
その後、ペースト１を塗布した透明電極１を電気炉内に移して、大気中、４５０℃の条件のもとで３０分間焼成した。次に、電気炉から透明電極１を取り出し、冷却した。このようにして、ＳｎＯ_２導電膜３上に図１に示す半導体電極２と同様の構成の半導体電極（受光面の面積；４ｃｍ^２、半導体膜からなる層の厚さ；８μｍ、ＴｉＯ_２の塗布量：１５ｇ／ｃｍ^２）を形成し、色素（金属錯体色素及び有機色素）を含有していない状態の光電極を作製した。
【０１２２】
その後、光電極の半導体電極の裏面に色素を以下のようにして吸着させた。先ず、増感色素として下記式（Ｉ）で表される色素（Ｒｅｄ　ｄｙｅ，　Ｓｏｌｏｒｏｎｉｘ社製、商品名：「Ｎ７１９」）を用い、これをエタノールとＤＭＦの混合溶媒（エタノールとＤＭＦの質量比；エタノール：ＤＭＦ＝１：１）に溶解させた溶液（増感色素の濃度；３×１０^−４ｍｏｌ／Ｌ）を調製した。次に、この溶液に半導体電極を浸漬し、暗所、２５℃の温度条件のもとで１２時間放置した。次に、この溶液から半導体電極を取り出してエタノールで洗浄し、暗所にて自然乾燥させた。これにより、半導体電極２の内部に増感色素を約１．２×１０^−７ｍｏｌ／ｍ^２吸着させた光電極１２を完成させた。
【０１２３】
【化２８】

【０１２４】
次に、上記の光電極と同様の形状と大きさを有する対極として、電子ビーム蒸着法によりＰｔが蒸着された透明導電性ガラス電極（Ｐｔ薄膜の厚さ；３ｎｍ）を作製した。
【０１２５】
また、電解液Ｅとして、式（Ａ１）に示したホウ素化合物を含むヨウ素系レドックス溶液（ヨウ化テトラブチルアンモニウムの濃度；０．６ｍｏｌ／Ｌ、ヨウ素の濃度；０．１ｍｏｌ／Ｌ、ホウ素化合物の濃度；０．１ｍｏｌ／Ｌ、溶媒；メトキシプロピオニトリル）を調製した。
【０１２６】
更に、半導体電極の大きさに合わせた形状を有する三井デュポンポリケミカル社製のスペーサＳ（商品名：「ハイミラン」）を準備した。次に、図３に示すように、光電極１２と対極ＣＥとスペーサＳを介して対向させた。そして、毛細管現象を利用することにより、スペーサＳと光電極１２又は対極ＣＥとの間の隙間からスペーサＳ、光電極１２及び対極ＣＥによりに画成された空間に上記の電解液Ｅを充填し、エポキシ樹脂により各部材間をシールして、色素増感型太陽電池を完成させた。
【０１２７】
（実施例２）
電解液Ｅとして、式（Ｂ１）に示したホウ素化合物含むヨウ素系レドックス溶液（ヨウ化テトラブチルアンモニウムの濃度；０．６ｍｏｌ／Ｌ、ヨウ素の濃度；０．１ｍｏｌ／Ｌ、ホウ素化合物の濃度；０．１ｍｏｌ／Ｌ、溶媒；メトキシプロピオニトリル）を調製した。この電解液Ｅを用いたこと以外は、実施例１と同様の手順及び条件で色素増感型太陽電池を作製した。
【０１２８】
（実施例３）
電解液Ｅとして、式（Ａ２）に示したホウ素化合物含むヨウ素系レドックス溶液（ヨウ化テトラブチルアンモニウムの濃度；０．６ｍｏｌ／Ｌ、ヨウ素の濃度；０．１ｍｏｌ／Ｌ、ホウ素化合物の濃度；０．１ｍｏｌ／Ｌ、溶媒；メトキシプロピオニトリル）を調製した。この電解液Ｅを用いたこと以外は、実施例１と同様の手順及び条件で色素増感型太陽電池を作製した。
【０１２９】
（実施例４）
電解液Ｅとして、式（Ａ３）に示したホウ素化合物含むヨウ素系レドックス溶液（ヨウ化テトラブチルアンモニウムの濃度；０．６ｍｏｌ／Ｌ、ヨウ素の濃度；０．１ｍｏｌ／Ｌ、ホウ素化合物の濃度；０．１ｍｏｌ／Ｌ、溶媒；メトキシプロピオニトリル）を調製した。この電解液Ｅを用いたこと以外は、実施例１と同様の手順及び条件で色素増感型太陽電池を作製した。
【０１３０】
（実施例５）
電解液Ｅとして、式（Ｄ１）に示したホウ素化合物含むヨウ素系レドックス溶液（ヨウ化テトラブチルアンモニウムの濃度；０．６ｍｏｌ／Ｌ、ヨウ素の濃度；０．１ｍｏｌ／Ｌ、ホウ素化合物の濃度；０．１ｍｏｌ／Ｌ、溶媒；メトキシプロピオニトリル）を調製した。この電解液Ｅを用いたこと以外は、実施例１と同様の手順及び条件で色素増感型太陽電池を作製した。
【０１３１】
（実施例６）
電解液Ｅとして、式（Ｃ１）に示したホウ素化合物含むヨウ素系レドックス溶液（ヨウ化テトラブチルアンモニウムの濃度；０．６ｍｏｌ／Ｌ、ヨウ素の濃度；０．１ｍｏｌ／Ｌ、ホウ素化合物の濃度；０．１ｍｏｌ／Ｌ、溶媒；メトキシプロピオニトリル）を調製した。この電解液Ｅを用いたこと以外は、実施例１と同様の手順及び条件で色素増感型太陽電池を作製した。
【０１３２】
（実施例７）
電解液Ｅとして、式（Ａ４）に示したホウ素化合物含むヨウ素系レドックス溶液（ヨウ化テトラブチルアンモニウムの濃度；０．６ｍｏｌ／Ｌ、ヨウ素の濃度；０．１ｍｏｌ／Ｌ、ホウ素化合物の濃度；０．１ｍｏｌ／Ｌ、溶媒；メトキシプロピオニトリル）を調製した。この電解液Ｅを用いたこと以外は、実施例１と同様の手順及び条件で色素増感型太陽電池を作製した。
【０１３３】
（実施例８）
電解液Ｅとして、式（Ｇ１）に示した化合物（東京化成社製、商品名：「フェニルホウ酸」）の脱水縮合物含むヨウ素系レドックス溶液（ヨウ化テトラブチルアンモニウムの濃度；０．６ｍｏｌ／Ｌ、ヨウ素の濃度；０．１ｍｏｌ／Ｌ、式（Ｇ１）に示した化合物の濃度；０．１ｍｏｌ／Ｌ、溶媒；メトキシプロピオニトリル）を調製した。この電解液Ｅを用いたこと以外は、実施例１と同様の手順及び条件で色素増感型太陽電池を作製した。
【０１３４】
（比較例１）
電解液Ｅとして、加水分解能を有するホウ素化合物を含まないヨウ素系レドックス溶液（ヨウ化テトラブチルアンモニウムの濃度；０．６ｍｏｌ／Ｌ、ヨウ素の濃度；０．１ｍｏｌ／Ｌ、溶媒；メトキシプロピオニトリル）を調製した。この電解液Ｅを用いたこと以外は、実施例１と同様の手順及び条件で色素増感型太陽電池を作製した。
【０１３５】
［電池特性試験１］
以下の手順及び測定条件により電池特性試験を行ない、実施例１〜実施例８及び比較例１の色素増感型太陽電池の光電変換効率ηを測定した。
【０１３６】
電池特性試験は、ソーラーシミュレータ（ワコム製、商品名；「ＷＸＳ−８５−Ｈ型」）を用い、ＡＭフィルター（ＡＭ１．５）を通したキセノンランプ光源から１０００ｍＷ／ｃｍ^２の擬似太陽光を照射することにより行った。
【０１３７】
先ず、各色素増感型太陽電池について、Ｉ−Ｖテスターを用いて室温にて電流−電圧特性を測定し、開放電圧（Ｖｏｃ／Ｖ）、短絡電流（Ｉｓｃ／ｍＡ・ｃｍ^−２）、曲線因子（Ｆ．Ｆ．）を求め、これらから起動初期の光電変換効率η［％］を求めた。
【０１３８】
その後、８５℃に保持した恒温槽に各色素増感型太陽電池を入れ、遮光状態でありかつ回路開放状態で保存し、３６０時間経過した後、恒温槽から取り出して、室温にて上記と同様の電流−電圧特性を測定し、３６０時間経過後の光電変換効率ηを求めた。その結果を表１に示す。
【０１３９】
【表１】

【０１４０】
表１に示した結果から明らかなように、本発明の色素増感型太陽電池に使用する加水分解能を有するホウ素化合物を含有させた電解質を用いた実施例１〜実施例８の色素増感型太陽電池は、８５℃という色素増感型太陽電池が実用化された際に最も適用される可能性の高い比較的高温の作動環境下で長期にわたり保存された後においても優れた光電変換効率をほぼ維持できることが確認された。一方、比較例１の色素増感型太陽電池は、保存時間の経過とともに光電変換効率が大幅に低下していることが確認された。
【０１４１】
［電池特性試験２］
実施例１と比較例１の色素増感型太陽電池を別途作製し、以下に示す手順及び条件以外は上述の電池特性試験１と同様の手順及び測定条件により電池特性試験を行ない、実施例１と比較例１の色素増感型太陽電池の光電変換効率ηを測定した。
【０１４２】
すなわち、実施例７と比較例１の色素増感型太陽電池をそれぞれ短絡させ、電解液Ｅの温度を６０℃に保持した状態とし、これに先に述べた１０００ｍＷ／ｃｍ^２の疑似太陽光を連続的に照射した。そして、疑似太陽光の照射開始から２４時間経過後、１２０時間経過後、２４０時間経過後の光電変換効率ηをそれぞれ測定した。その結果を表２に示す。
【０１４３】
【表２】

【０１４４】
表２に示した結果から明らかなように、実施例１の色素増感型太陽電池は、６０℃の作動環境下で長期にわたり疑似太陽光の照射を受けて連続的に作動させられた後においても優れた光電変換効率を維持できることが確認された。一方、実施例１の色素増感型太陽電池に比較して、比較例１の色素増感型太陽電池は、疑似太陽光の照射時間の経過とともに光電変換性能が大幅に低下していることが確認された。
【０１４５】
【発明の効果】
以上説明したように、本発明によれば、電解質中に酸化防止剤が含有されているので、色素（金属錯体色素及び有機色素）の耐熱性、耐光性及び化学的安定性を容易に向上させることができ、優れた光電変換効率を長期にわたり得ることができる色素増感型太陽電池を容易に構成することができる。
【図面の簡単な説明】
【図１】本発明の色素増感型太陽電池の第１実施形態の基本構成を示す模式断面図である。
【図２】本発明の色素増感型太陽電池の第２実施形態の基本構成を示す模式断面図である。
【図３】図２に示した色素増感型太陽電池を複数併設する場合の一例を示す模式断面図である。
【符号の説明】
１…透明電極、２…半導体電極、３…透明導電膜、４…透明基板、５…シール材、６・・・透明基板、１０…光電極，２０，３０，４０…色素増感型太陽電池、ＣＥ…対極、Ｅ…電解液、Ｆ１，Ｆ２，Ｆ３，…受光面、Ｆ２２…半導体電極２の裏面、Ｌ１０…入射光、Ｓ…スペーサ、ＰＳ…多孔体層。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a dye-sensitized solar cell.
[0002]
[Prior art]
In recent years, various developments of solar cells have been promoted with increasing interest in global warming and energy problems. Among the solar cells, a dye-sensitized solar cell disclosed in US Pat. No. 4,927,721 is a photoelectrode (working electrode) having a titanium dioxide porous thin film containing a ruthenium complex dye as a metal complex dye (sensitizing dye). ), The materials used (such as oxide semiconductors) are inexpensive, the materials used can be used without being highly purified, can be manufactured by a relatively simple process, and the metal complex dyes used Since the absorption wavelength region is broad, practical use is expected from the fact that light in almost all wavelength regions of visible light can be converted into electricity.
[0003]
And as a metal complex dye used for a dye-sensitized solar cell, conventionally, for example, ruthenium (Ru)³⁺Ion, Ru²⁺Isothiocyanate complex having a thionocyanate ion, 1,10-phenanthroline, 1,10-phenanthroline derivative, 2,2′-bipyridyl and 2,2′-bipyridyl derivative as a ligand. Known are formula (I) described later), thiocyanate complexes, porphyrin dyes, phthalocyanine dyes, and the like.
[0004]
In addition to metal complex dyes, organic dyes may also be used. Such organic dyes include xanthene dyes, cyanine dyes, merocyanine dyes, phenylxanthene dyes, triphenylmethane dyes, rhodacyanine. System dyes and the like are known.
[0005]
In the dye-sensitized solar cell, while improving the battery characteristics (photoelectric conversion efficiency), improving the battery life to a practical level is an important issue for practical use. That is, it is possible to reduce deterioration of battery characteristics during long-term use and to obtain excellent battery characteristics over a long period of time.
[0006]
One approach to this is to improve the durability of the metal complex dyes and organic dyes contained in the semiconductor electrode of the photoelectrode to heat, light, and chemicals, and to extend their lifespan. Various studies have been made to construct a battery that can be obtained.
[0007]
As said examination, the metal complex pigment | dye described in Unexamined-Japanese-Patent No. 2002-25635 is mentioned, for example.
[0008]
[Patent Document 1]
US Pat. No. 4,927,721
[Patent Document 2]
JP 2002-25635 A
[0009]
[Problems to be solved by the invention]
However, the present inventors have not been able to obtain sufficient heat resistance, light resistance and chemical stability even with the metal complex dye described in JP-A-2002-25635, and therefore It has been found that even a dye-sensitized solar cell provided with a photoelectrode containing this dye is still insufficient because the photoelectric conversion efficiency at the start of use cannot be stably obtained over a long period of time.
[0010]
That is, a conventional metal complex dye including the metal complex dye described in the above publication is used as a sensitizer for a photoelectric conversion reaction by being contained in a semiconductor electrode constituting a photoelectrode, and is irradiated with light such as sunlight. However, there was a problem that the metal complex dye decomposes and deteriorates when the photoelectric conversion reaction is continued.
[0011]
In addition, active oxygen species (for example, hydroperoxy radical, alkyl peroxy radical, hydroxy radical, hydrogen peroxide, alkyl hydroperoxide, singlet oxygen, generated in the electrolyte or in the semiconductor electrode in contact with the electrolyte by this light or heat, (Atomic oxygen, ozone, superoxide anion, peroxide anion, oxygen anion, etc.) have a problem that the metal complex dye is oxidatively decomposed.
[0012]
There is also a problem that the metal complex dye is photodegraded by absorption of ultraviolet light contained in the light. Further, the above-mentioned problem has occurred in the same manner when an organic dye is used instead of the metal complex dye.
[0013]
Furthermore, the progress of the above-described decomposition of the dye (oxidative decomposition, photodecomposition, thermal decomposition) is, for example, a relatively high temperature (for example, most likely to be applied when a dye-sensitized solar cell is put to practical use). When installed in an operating environment (for example, outdoors, etc.) of 60 ° C. or higher), there was a tendency to become more prominent.
[0014]
Therefore, the conventional dye-sensitized solar cell cannot obtain a sufficient battery life because the deterioration due to the decomposition of the metal complex dye and the organic dye is greatly affected.
[0015]
The present invention has been made in view of the above-described problems of the prior art, and can easily improve the heat resistance, light resistance and chemical stability of the dye, and can obtain excellent photoelectric conversion efficiency over a long period of time. It is an object to provide a dye-sensitized solar cell that can be used.
[0016]
[Means for Solving the Problems]
As a result of intensive studies to achieve the above object, the present inventors have conducted a decomposition reaction of dyes (metal complex dyes and organic dyes) when water is present in the battery system (especially in an electrolyte containing an organic solvent). Has been found to be significantly promoted. The present inventors have found that it is extremely effective to prevent the progress of the decomposition reaction of the dye by adding a specific additive that decomposes water into the electrolyte rather than changing the molecular structure of the dye itself. The present invention has been reached.
[0017]
That is, the present invention includes a photoelectrode having a semiconductor electrode having a light receiving surface, a transparent electrode disposed adjacently on the light receiving surface, and a counter electrode, and the semiconductor electrode and the counter electrode are interposed via an electrolyte. A dye-sensitized solar cell disposed oppositely, wherein the semiconductor electrode contains a dye, and the electrolyte contains a boron compound having hydrolytic ability. Type solar cell is provided.
[0018]
Here, in the present invention, the “dye” refers to a metal complex dye and an organic dye. In addition, “electrolyte” refers to an electrolyte solution (hereinafter referred to as “electrolyte” as necessary), a gel obtained by adding a gelling agent to the electrolyte solution, and a solid electrolyte. Furthermore, the “boron compound having hydrolytic ability” refers to a boron compound having a structure in which at least one characteristic group having hydrolytic ability is bonded to a boron atom.
[0019]
According to the present invention, by containing a boron compound having hydrolytic ability in the electrolyte, deterioration due to oxidation of the dye (metal complex dye and organic dye) is sufficient over a long period of time even under irradiation of light such as sunlight. To be prevented. That is, the heat resistance, light resistance and chemical stability of the dye (metal complex dye and organic dye) can be easily improved. As a result, a dye-sensitized solar cell capable of obtaining excellent photoelectric conversion efficiency over a long period can be easily configured.
[0020]
As described above, the reason why the decomposition reaction of dyes (metal complex dyes and organic dyes) is significantly accelerated when water is present in the battery system (especially in an electrolyte containing an organic solvent) is clearly elucidated. However, the present inventors consider as follows.
[0021]
That is, the present inventors are semiconductors that constitute a semiconductor electrode when light is irradiated to the battery when water is present in the battery system due to water outside the battery or water mixed in the manufacturing process. (For example, titanium oxide), a dye molecule, or a molecule in an electrolyte (for example, an organic solvent molecule in an electrolytic solution or an oxygen molecule dissolved in the electrolytic solution) is excited, and an electron or energy transfer reaction proceeds. It is considered that the above-mentioned active oxygen species and other radical species are likely to be generated, and these are likely to react with the dye to cause decomposition of the dye or a decrease in the photosensitization function of the dye.
[0022]
Further, when water is present in the battery system, the ligand exchange reaction of the dye is likely to proceed. From this viewpoint, it is considered that the dye is easily decomposed or the photosensitization function of the dye is easily lowered. . In such a ligand exchange reaction of a dye, when a so-called Red dye (a dye having a structure represented by the formula (I) described later) is used as the dye, for example, a ligand constituting Red dye NCS⁻Is the ligand OH⁻The reaction etc. which replace | exchange is considered.
[0023]
Further, although the reason why the decomposition of the dye is sufficiently prevented by including a boron compound having hydrolytic ability in the electrolyte has not been clearly clarified, the present inventors consider as follows. .
[0024]
In other words, among the compounds having hydrolytic ability, boron compounds having hydrolytic ability can exist chemically and stably for a long time in the electrolyte (or in a state of being adsorbed in the photoelectrode or the counter electrode), and hydrolyzes bonded to the boron atom. It is considered that the characteristic group having the property has high reactivity with respect to the hydrolysis reaction, and the reaction product (boric acid ester, alcohol, boric acid, thiol, etc.) does not inhibit the battery reaction. ing.
[0025]
For example, a boron compound having hydrolytic ability generates alcohol by consuming water by hydrolysis. Since this alcohol is relatively strong and easily coordinated to the boron compound, there is an advantage that the decomposition of the dye is difficult to proceed by removing the alcohol from the system.
[0026]
Further, according to the present invention, by containing a boron compound having hydrolytic ability in an electrolyte (for example, an electrolytic solution), oxidation of the electrolyte (for example, the electrolytic solution) itself due to generation of the active oxygen species by light or heat. The reaction can also be sufficiently prevented. Furthermore, by including a boron compound having hydrolytic ability in an electrolyte (for example, an electrolytic solution), photolysis and thermal decomposition of the electrolyte itself by light and heat can be sufficiently prevented. Also from such a viewpoint, according to the present invention, a dye-sensitized solar cell capable of obtaining excellent photoelectric conversion efficiency over a long period of time can be easily configured.
[0027]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the photoelectrode and the dye-sensitized solar cell of the present invention will be described in detail with reference to the drawings. In the following description, the same or corresponding parts are denoted by the same reference numerals, and redundant description is omitted.
[0028]
[First Embodiment]
FIG. 1 is a schematic cross-sectional view showing the basic configuration of the first embodiment of the dye-sensitized solar cell of the present invention.
[0029]
The dye-sensitized solar cell 20 shown in FIG. 1 mainly includes a photoelectrode 10, a counter electrode CE, and an electrolyte E filled in a gap formed between the photoelectrode 10 and the counter electrode CE by a spacer S. It is configured. 1 mainly includes a semiconductor electrode 2 having a light receiving surface F2 and a transparent electrode 1 disposed adjacently on the light receiving surface F2 of the semiconductor electrode 2. The semiconductor electrode 2 is in contact with the electrolytic solution E on the back surface F22 opposite to the light receiving surface F2.
[0030]
In the dye-sensitized solar cell 20, the sensitizing dye adsorbed in the semiconductor electrode 2 is excited by the light L <b> 10 that passes through the transparent electrode 1 and is applied to the semiconductor electrode 2. Electrons are injected into the electrode 2. The electrons injected in the semiconductor electrode 2 are collected by the transparent electrode 1 and taken out to the outside.
[0031]
The structure of the transparent electrode 1 is not specifically limited, The transparent electrode mounted in a normal dye-sensitized solar cell can be used. For example, the transparent electrode 1 shown in FIG. 1 has a configuration in which a so-called transparent conductive film 3 is coated on the semiconductor electrode 2 side of a transparent substrate 4 such as a glass substrate. As the transparent conductive film 3, a transparent electrode used for a liquid crystal panel or the like may be used.
[0032]
For example, fluorine-doped SnO₂Coated glass, ITO coated glass, ZnO: Al coated glass, antimony-doped tin oxide (SnO₂-Sb), etc. In addition, a transparent electrode obtained by doping cations or anions with different valences into tin oxide or indium oxide, or a metal electrode having a structure capable of transmitting light, such as a mesh shape or a stripe shape, provided on a substrate such as a glass substrate Good.
[0033]
As the transparent substrate 4, a transparent substrate used for a liquid crystal panel or the like may be used. Specific examples of the transparent substrate material include transparent glass substrates, materials that prevent the reflection of light by appropriately roughening the surface of the glass substrate, and materials that transmit light, such as a ground glass-like translucent glass substrate. Note that the material may not be glass as long as it transmits light, and may be a transparent plastic plate, a transparent plastic film, an inorganic transparent crystal, or the like.
[0034]
A semiconductor electrode 2 shown in FIG. 1 is composed of an oxide semiconductor layer containing oxide semiconductor particles as a constituent material. The oxide semiconductor particles contained in the semiconductor electrode 2 are not particularly limited, and a known oxide semiconductor or the like can be used. As an oxide semiconductor, for example, TiO₂, ZnO, SnO₂, Nb₂O₅, In₂O₃, WO₃, ZrO₂, La₂O₃, Ta₂O₅, SrTiO₃, BaTiO₃Etc. can be used. Among these oxide semiconductors, anatase TiO₂Is preferred.
[0035]
The sensitizing dye contained in the semiconductor electrode 2 is not particularly limited as long as it is a dye having absorption in the visible light region and / or the infrared light region. More preferably, any material that emits electrons when excited by light having a wavelength of at least 200 nm to 10 μm may be used. As such a sensitizing dye, a metal complex, an organic dye, or the like can be used. Examples of the metal complex include metal phthalocyanines such as copper phthalocyanine and titanyl phthalocyanine, chlorophyll or derivatives thereof, hemin, ruthenium, osmium, iron and zinc complexes (for example, cis-dicyanate-N, N′-bis (2,2′-bipyridyl). -4,4'-dicarboxylate) ruthenium (II)) and the like. As the organic dye, metal-free phthalocyanine, cyanine dye, merocyanine dye, xanthene dye, triphenylmethane dye, and the like can be used.
[0036]
The counter electrode CE is a redox pair in the electrolyte (for example, I₃ ⁻/ I⁻Etc.) is not particularly limited as long as it is made of a material that can pass electrons with high efficiency. For example, the same counter electrode normally used for silicon solar cells, liquid crystal panels, etc. May be used. For example, it may have the same configuration as that of the transparent electrode 1 described above. A metal thin film electrode such as Pt is formed on the transparent conductive film 3 similar to the transparent electrode 1, and the metal thin film electrode is disposed on the side of the electrolyte E. You may arrange | position toward. Alternatively, a small amount of platinum may be attached to the transparent conductive film 3 of the transparent electrode 1, or a metal thin film such as platinum, a conductive film such as carbon, or the like may be used.
[0037]
Further, the electrolytic solution E is particularly limited as long as it contains the boron compound having the hydrolytic ability described above and contains a redox species for reducing the dye after photoexcitation and electron injection into the semiconductor. For example, it may be a liquid electrolyte, or a gel electrolyte obtained by adding a known gelling agent (polymer or low-molecular gelling agent) thereto.
[0038]
The solvent used in the electrolytic solution E is not particularly limited as long as it is a compound that can dissolve the solute component, but is electrochemically inert, has a high relative dielectric constant, and a low viscosity (and these solvents). For example, nitrile compounds such as methoxypropionitrile and acetonitrile, lactone compounds such as γ-butyrolactone and valerolactone, carbonate compounds such as ethylene carbonate and propylene carbonate, and carbonic acid. And propylene.
[0039]
As the solute used in the electrolytic solution E, a redox couple (I) capable of transferring electrons to and from the dye supported on the semiconductor electrode 2 or the counter electrode CE.₃ ⁻/ I⁻System electrolyte, Br₃ ⁻/ Br⁻Based electrolytes, redox electrolytes such as hydroquinone / quinone based electrolytes), compounds having an effect of promoting the transfer of electrons, and the like. These may be included singly or in combination.
[0040]
More specifically, examples of the substance constituting the redox pair include halogens such as iodine, bromine, and chlorine, halides such as dimethylpropylimidazolium iodide, tetrapropylammonium iodide, and lithium iodide. Can be mentioned. Examples of the additive for efficiently transferring electrons include heterocyclic compounds such as 4-t-butylpyridine and N-methylbenzimidazole.
[0041]
The boron compound having hydrolytic ability added to the electrolytic solution E is preferably a compound represented by the following general formula (1).
[0042]
[Chemical 7]

[0043]
Here, in Formula (1), n shows the integer of 1-3, X shows the characteristic group which has a hydrolytic ability, R¹Represents at least one hydrocarbon group selected from the group consisting of alkyl groups, alkenyl groups, alkynyl groups, allyl groups, aryl groups, and heterocyclic groups.
[0044]
In this specification, “heterocyclic group” means pyrrole, pyrroline, oxazole, isoxazole, thiazole, isothiazole, imidazole, imidazoline, pyrazole, triazole, furazane, tetrazole, pyran, thiin, pyridine, oxazine, thiazine. , Pyritazine, pyrimidine, pyrazine, triazine, benzofuran, isobenzofuran, benzothiophene, indole, isoindole, benzoxazole, benzothiazole, indazole, benzimidazole, chromene, chroman, quinoline, isoquinoline, cinnoline, phthalazine, quinazoline, quinoxaline, dibenzofuran , Carbazole, xanthene, acridine, phenanthridine, phenanthroline, phenazine, phenoxazine, thianthre Shows indolizine, tinoridine, naphthyridine, purine, and, at least one member selected from the group consisting of pteridine.
[0045]
In addition, long-term chemical stability of the boron compound with hydrolytic ability in the electrolyte and sufficient reactivity to the hydrolysis reaction are ensured, and the inhibition of the reaction product of the hydrolysis reaction to the battery reaction is sufficiently reduced. From the viewpoint of¹The alkyl group to be preferably has 1 to 20 carbon atoms, R¹The number of carbon atoms in the alkenyl group is preferably 2-20, and R¹The alkynyl group is preferably having 2 to 20 carbon atoms.
[0046]
From the same viewpoint as described above, X in the formula (1) is preferably at least one selected from the group consisting of the following general formulas (2) to (5) and a halogen atom.
[0047]
[Chemical 8]

[0048]
[Chemical 9]

[0049]
Embedded image

[0050]
Embedded image

[0051]
Here, in the formulas (2) to (5), R¹Is R in the formula (1)¹Is synonymous with R²And R³May be the same or different, and each independently represents at least one selected from the group consisting of a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an allyl group, an aryl group, and a heterocyclic group. R⁴, R⁵And R⁶May be the same or different, and each independently represents at least one selected from the group consisting of a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an allyl group, an aryl group, and a heterocyclic group. Show.
[0052]
In addition, long-term chemical stability of the boron compound with hydrolytic ability in the electrolyte and sufficient reactivity to the hydrolysis reaction are ensured, and the inhibition of the reaction product of the hydrolysis reaction to the battery reaction is sufficiently reduced. From the viewpoint of², R³, R⁴, R⁵Or R⁶The alkyl group to be preferably has 1 to 20 carbon atoms, R², R³, R⁴, R⁵Or R⁶The alkenyl group is preferably having 2 to 20 carbon atoms, R², R³, R⁴, R⁵Or R⁶The alkynyl group is preferably having 2 to 20 carbon atoms.
[0053]
Further, from the viewpoint of more reliably preventing the progress of oxidative decomposition, photolysis and thermal decomposition of the dye (metal complex dye and organic dye) and the electrolytic solution E, R in the formulas (1) to (4)¹At least one hydrogen atom comprising a sulfo group, a sulfino group, a sulfeno group (-SO-), an oxycarbonyl group (-CO-O-), a haloformyl group, a carbamoyl group, a hydrazinocarbonyl group (-CO-NH -NH₂), Amidino group, cyano group, isocyano group, cyanato group, isocyanato group, thiocyanato group, isothiocyanato group, formyl group, oxo group, thioformyl group, thioxo group, mercapto group, amino group, imino group, hydrazino group, allyloxy group ( -O-R_A), Sulfide groups (-SR⁴), At least one substituent selected from the group consisting of a nitro group, a silyl group and a halogen atom. The above “R”⁴"Represents an alkyl group having 1 to 50 carbon atoms or an aromatic substituent. In addition, the above “R_A"Indicates an aromatic substituent.
[0054]
Further, as described above, R in the formula (4) is used from the viewpoint of sufficiently preventing the oxidative decomposition, photodecomposition and thermal decomposition of the dye (metal complex dye and organic dye) and the electrolytic solution E.²And R³At least one of them is preferably at least one selected from the group consisting of an alkyl group, an alkenyl group, an alkynyl group, an allyl group, an aryl group, and a heterocyclic group.
[0055]
Further, in this case, R in the formula (4)²And R³At least one of the hydrogen atoms is a sulfo group, a sulfino group, a sulfeno group (—SO—), an oxycarbonyl group (—CO—O—), a haloformyl group, a carbamoyl group, a hydrazinocarbonyl group. (-CO-NH-NH₂), Amidino group, cyano group, isocyano group, cyanato group, isocyanato group, thiocyanato group, isothiocyanato group, formyl group, oxo group, thioformyl group, thioxo group, mercapto group, amino group, imino group, hydrazino group, allyloxy group ( -O-R_A), Sulfide groups (-SR⁴), At least one substituent selected from the group consisting of a nitro group, a silyl group and a halogen atom. The above “R”⁴"Represents an alkyl group having 1 to 50 carbon atoms or an aromatic substituent. In addition, the above “R_A"Indicates an aromatic substituent.
[0056]
In addition, as described above, R in the formula (5) is used from the viewpoint of more sufficiently preventing the oxidative decomposition, photolysis, and thermal decomposition of the dye (metal complex dye and organic dye) and the electrolytic solution E.⁴, R⁵And R⁶It is preferable that at least one of them is at least one selected from the group consisting of an alkyl group, an alkenyl group, an alkynyl group, an allyl group, an aryl group, and a heterocyclic group.
[0057]
Further, in this case, R in the formula (5)⁴, R⁵And R⁶At least one hydrogen atom constituting at least one of the following is a sulfo group, a sulfino group, a sulfeno group (—SO—), an oxycarbonyl group (—CO—O—), a haloformyl group, a carbamoyl group, a hydrazinocarbonyl group. Group (—CO—NH—NH₂), Amidino group, cyano group, isocyano group, cyanato group, isocyanato group, thiocyanato group, isothiocyanato group, formyl group, oxo group, thioformyl group, thioxo group, mercapto group, amino group, imino group, hydrazino group, allyloxy group ( -O-R_A), Sulfide groups (-SR⁴), At least one substituent selected from the group consisting of a nitro group, a silyl group and a halogen atom. The above “R”⁴"Represents an alkyl group having 1 to 50 carbon atoms or an aromatic substituent. In addition, the above “R_A"Indicates an aromatic substituent.
[0058]
Preferable specific examples of the boron compound having hydrolytic ability represented by the formula (1) described above include compounds represented by the following chemical formulas (A1) to (A4).
[0059]
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[0060]
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[0061]
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[0062]
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[0063]
Further, the boron compound having hydrolytic ability may have a structure in which two or more compounds represented by the formula (1) are bonded. Here, “a structure in which two or more compounds represented by the formula (1) are bonded” indicates the following structure. That is, a structure in which two or more compounds represented by the formula (1) form a covalent bond between the respective characteristic groups X, each hydrocarbon group R¹A structure in which a covalent bond is formed between them, or one characteristic group X and the other hydrocarbon group R¹The structure which formed the covalent bond between is shown.
[0064]
For example, as a compound having a structure in which two compounds represented by the formula (1) form a covalent bond between the respective characteristic groups X, a compound represented by the following formula (B1) may be mentioned.
[0065]
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[0066]
Further, the boron compound having hydrolytic ability may be a compound represented by the following general formula (7).
[0067]
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[0068]
Here, in formula (7), R⁷, R⁸, R⁹And R¹⁰Are R in formula (1), respectively.¹Or a group having the same meaning as R⁷, R⁸, R⁹And R¹⁰At least one of them is a group having the same meaning as X in formula (1), and a group other than the group having the same meaning as X is R in formula (1).¹Is synonymous with In addition, as a boron compound which has hydrolytic ability, the compound which substituted the oxygen atom in Formula (7) by S other than the compound represented by Formula (7) is mentioned.
[0069]
For example, as a compound represented by Formula (7), the compound represented by a following formula (C1) is mentioned, for example.
[0070]
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[0071]
Further, the boron compound having hydrolytic ability may be a compound represented by the following general formula (8).
[0072]
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[0073]
Here, in formula (7), R¹¹, R¹², R¹³And R¹⁴Is R¹¹, R¹², R¹³And R¹⁴At least one of them is a group having the same meaning as X in formula (1), and a group other than the group having the same meaning as X is R in formula (1).¹Is synonymous with
[0074]
For example, as a compound represented by Formula (8), the compound represented by a following formula (D1) is mentioned, for example.
[0075]
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[0076]
Furthermore, the boron compound having hydrolytic ability may be a reaction product obtained by subjecting two or more compounds represented by the following general formula (6) to an intermolecular dehydration reaction. Here, in the following formula (6), m represents an integer of 1 to 3, and R¹R in formula (1)¹It is synonymous with.
Embedded image

[0077]
In this case as well, the long-term chemical stability of the boron compound having hydrolytic ability in the electrolyte and the sufficient reactivity to the hydrolysis reaction are ensured, and the inhibition of the reaction product of the hydrolysis reaction on the battery reaction is also achieved. From the viewpoint of sufficiently reducing R¹The alkyl group to be preferably has 1 to 20 carbon atoms, R¹The number of carbon atoms in the alkenyl group is preferably 2-20, and R¹The alkynyl group is preferably having 2 to 20 carbon atoms.
[0078]
Furthermore, from the viewpoint of more reliably preventing the progress of oxidative decomposition, photolysis and thermal decomposition of the dye (metal complex dye and organic dye) and the electrolytic solution E, R in the formula (6)¹At least one hydrogen atom comprising a sulfo group, a sulfino group, a sulfeno group (-SO-), an oxycarbonyl group (-CO-O-), a haloformyl group, a carbamoyl group, a hydrazinocarbonyl group (-CO-NH -NH₂), Amidino group, cyano group, isocyano group, cyanato group, isocyanato group, thiocyanato group, isothiocyanato group, formyl group, oxo group, thioformyl group, thioxo group, mercapto group, amino group, imino group, hydrazino group, allyloxy group ( -O-R_A), Sulfide groups (-SR⁴), At least one substituent selected from the group consisting of a nitro group, a silyl group and a halogen atom. The above “R”⁴"Represents an alkyl group having 1 to 50 carbon atoms or an aromatic substituent. In addition, the above “R_A"Indicates an aromatic substituent.
[0079]
For example, as a compound represented by Formula (6), the compound represented by a following formula (G1) is mentioned, for example. Examples of the reaction product obtained by the intermolecular dehydration reaction of the compound represented by the following formula (G1) include the following formulas (G2) and (G3).
[0080]
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[0081]
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[0082]
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[0083]
Furthermore, the boron compound having hydrolytic ability may be a reaction product obtained by subjecting two or more compounds represented by the following general formula (9) to a condensation reaction. Here, in the following formula (9), m represents an integer of 1 to 3, and R¹R in formula (1)¹It is synonymous with. In this case, as a by-product, for example, H₂S generates.
[0084]
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[0085]
In addition, the boron compound having hydrolytic ability may be a reaction product obtained by intermolecular dehydration reaction of two or more compounds represented by the following general formula (10). Here, in the following formula (10), m represents an integer of 1 to 3, and R¹R in formula (1)¹It is synonymous with. In this case, as a by-product, for example, NH₃Produces.
[0086]
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[0087]
Furthermore, the boron compound having hydrolytic ability may be a reaction product obtained by subjecting two or more compounds represented by the following general formula (11) to an intermolecular dehydration reaction. Here, in the following formula (11), m represents an integer of 1 to 3, and R¹R in formula (1)¹It is synonymous with. In this case, as a by-product, for example, R¹ ₃Si (OH) is generated.
[0088]
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[0089]
In addition, you may use simultaneously the boron compound which has all the hydrolysis ability demonstrated above arbitrarily combining what has a different structure.
[0090]
Moreover, it is preferable that the density | concentration of the boron compound which has the hydrolytic ability in the electrolyte solution E is 1 mmol / L-1 mol / L. When the concentration of the boron compound having hydrolytic ability is less than 1 mmol / L, there is a greater tendency that the effect of preventing the decomposition of the dye (metal complex dye and organic dye) cannot be sufficiently obtained. Moreover, when the concentration of the boron compound having hydrolytic ability exceeds 1 mol / L, the tendency to become difficult to dissolve in the electrolytic solution E increases.
[0091]
Further, the electrolytic solution E may further contain an ultraviolet absorber. By containing the ultraviolet absorber in the electrolyte E, among the light irradiated to the photoelectrode 10, ultraviolet rays that greatly affect the deterioration of the photosensitizing function of the dye (metal complex dye and organic dye) are selectively used. Thus, the dye (metal complex dye and organic dye) can be held in a more stabilized state in the electrolyte.
[0092]
The constituent material of the spacer S is not particularly limited, and for example, silica beads or the like can be used.
[0093]
Moreover, as a sealing material used for integrating the photoelectrode 10, the counter electrode CE, and the spacer S for the purpose of sealing the electrolytic solution E, it can be sealed so that the components of the electrolytic solution E do not leak to the outside as much as possible. Any material can be used as long as it is not particularly limited. For example, an epoxy resin, a silicone resin, an ethylene / methacrylic acid copolymer, a thermoplastic resin made of surface-treated polyethylene, or the like can be used.
[0094]
Next, an example of a method for manufacturing the dye-sensitized solar cell 20 shown in FIG. 1 will be described.
[0095]
When the transparent electrode 1 is manufactured, the fluorine-doped SnO described above on the substrate 4 such as a glass substrate.₂It can form using well-known thin film manufacturing techniques, such as spray-coating the transparent conductive films 3, such as. For example, in addition to this, it can be formed using a known thin film manufacturing technique such as a vacuum deposition method, a sputtering method, a CVD method, and a sol-gel method.
[0096]
Examples of a method for forming the semiconductor electrode 2 on the transparent conductive film 3 of the transparent electrode 1 include the following methods. That is, first, a dispersion liquid in which oxide semiconductor particles having a predetermined size (for example, a particle diameter of about 10 to 30 nm) is dispersed is prepared. The solvent of this dispersion liquid is not particularly limited as long as it can disperse oxide semiconductor particles such as water, an organic solvent, or a mixed solvent of both. Moreover, you may add surfactant and a viscosity modifier to a dispersion liquid as needed.
[0097]
Next, the dispersion is applied on the transparent conductive film 3 of the transparent electrode 1 and then dried. As a coating method at this time, a bar coater method, a printing method, or the like can be used. After drying, the semiconductor electrode 2 (porous semiconductor film) is formed by heating and baking in air, inert gas or nitrogen.
[0098]
Next, a dye is contained in the semiconductor electrode 2 by a known technique such as an immersion method. The sensitizing dye is contained by adhering to the semiconductor electrode 2 (chemical adsorption, physical adsorption or deposition). As this adhesion method, for example, a method of immersing the semiconductor electrode 2 in a solution containing a dye can be used. At this time, the adsorption and deposition of the dye can be promoted by heating and refluxing the solution. At this time, a metal such as silver or a metal oxide such as alumina may be contained in the semiconductor electrode 2 in addition to the pigment, if necessary.
[0099]
Further, the surface oxidation treatment for removing impurities that inhibit the photoelectric conversion reaction contained in the semiconductor electrode 2 may be appropriately performed by a known method every time each layer is formed or when all the layers are formed. .
[0100]
Other methods for forming the semiconductor electrode 2 on the transparent conductive film 3 of the transparent electrode 1 include the following methods. That is, on the transparent conductive film 3 of the transparent electrode 1 TiO₂A method of vapor-depositing a semiconductor such as a film may be used. As a method for depositing a semiconductor on the transparent conductive film 3, a known thin film manufacturing technique can be used. For example, a physical vapor deposition method such as electron beam vapor deposition, resistance heating vapor deposition, sputter vapor deposition, or cluster ion beam vapor deposition may be used. Metal or the like is evaporated in a reactive gas such as oxygen, and the reaction product is converted into the transparent conductive film 3. A reactive vapor deposition method may be used. Furthermore, chemical vapor deposition such as CVD can be used by controlling the flow of the reaction gas.
[0101]
After the photoelectrode 10 is produced in this manner, for example, a counter electrode CE is produced by a known thin film manufacturing technique similar to the method used for producing the photoelectrode 10, and as shown in FIG. The counter electrode CE is assembled so as to be opposed to each other through the spacer S. At this time, the space formed between the photoelectrode 10 and the counter electrode CE by the spacer S is filled with the electrolytic solution E containing the components described above, and the dye-sensitized solar cell 20 is completed.
[0102]
[Second Embodiment]
FIG. 2 is a schematic cross-sectional view showing a second embodiment of the dye-sensitized solar cell of the present invention. Hereinafter, the dye-sensitized solar cell 30 illustrated in FIG. 2 will be described. In addition, the same code | symbol is attached | subjected about the element same as the element demonstrated regarding the dye-sensitized solar cell 20 shown in the above-mentioned FIG. 1, and the overlapping description is abbreviate | omitted.
[0103]
A dye-sensitized solar cell 30 shown in FIG. 2 uses the photoelectrode 10 shown in FIG. 1 and a counter electrode CE similar to the counter electrode CE shown in FIG. In the dye-sensitized solar cell 20 shown in FIG. 1, the space formed between the photoelectrode 10 and the counter electrode CE is filled with the electrolytic solution E by the spacer S, as shown in FIG. In the dye-sensitized solar cell 30, the porous layer PS is disposed between the photoelectrode 10 and the counter electrode CE. And the transparent substrate 6 is arrange | positioned at the surface on the opposite side to the porous body layer PS of counter electrode CE.
[0104]
The porous body layer PS has a structure having a large number of pores, and the porous body layer PS has an electrolysis similar to that used in the dye-sensitized solar cell 20 shown in FIG. Liquid E is filled and held.
[0105]
The electrolytic solution E is also held in the counter electrode CE in the semiconductor electrode 2 or depending on the constituent material used (for example, a porous conductive film such as carbon). The side surfaces of the semiconductor electrode 2, the porous body layer PS, and the counter electrode CE of the dye-sensitized solar cell 30 illustrated in FIG. 2 are exposed to the outside from the side surfaces of the semiconductor electrode 2, the porous body layer PS, and the counter electrode CE. In order to prevent leakage, it is covered with a sealing material 5.
[0106]
The porous body layer PS is not particularly limited as long as the porous body layer PS can hold the electrolytic solution E and does not have electron conductivity. For example, you may use the porous body formed with the rutile type titanium oxide particle. Examples of constituent materials other than rutile type titanium oxide include zirconia, alumina, and silica.
[0107]
Moreover, as the sealing material 5, for example, a thermoplastic resin film such as polyethylene or an epoxy adhesive can be used. As the transparent substrate 6 disposed on the counter electrode CE side, a substrate similar to the transparent substrate 4 used for the transparent electrode 1 of the photoelectrode 10 can be used.
[0108]
Next, an example of a method for manufacturing the dye-sensitized solar cell 30 shown in FIG. 2 will be described. First, the photoelectrode 10 is produced in the same manner as the dye-sensitized solar cell 20 shown in FIG. Next, the porous layer PS is formed on the surface F22 of the semiconductor electrode 2 of the photoelectrode 10 by the same procedure as that for producing the semiconductor electrode 2 of the photoelectrode 10. For example, a dispersion (slurry) containing a constituent material of the porous layer PS such as rutile type titanium oxide may be prepared, and this may be applied to the surface F22 of the semiconductor electrode 2 and dried.
[0109]
For the counter electrode CE, for example, when a porous conductive film such as carbon is used as the counter electrode CE, for example, a carbon paste is prepared, and this is applied to the surface of the porous body layer PS and dried. May be formed. Then, the transparent substrate 6 is formed on the surface opposite to the porous layer PS side of the counter electrode CE by a known thin film manufacturing technique, and the side surfaces of the semiconductor electrode 2, the porous layer PS and the counter electrode CE are sealed with the sealing material 5. To complete the dye-sensitized solar cell 30.
[0110]
The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment.
[0111]
For example, the dye-sensitized solar cell of the present invention may have a module form in which a plurality of batteries are provided as in the dye-sensitized solar cell 40 shown in FIG. A dye-sensitized solar cell 40 shown in FIG. 3 shows an example in which a plurality of dye-sensitized solar cells 30 shown in FIG. 2 are provided in series.
[0112]
Compared to the dye-sensitized solar cell 30 shown in FIG. 2, the dye-sensitized solar cell 40 shown in FIG. 3 is different from the seal material 5 provided between the photoelectrodes 10 of single cells of adjacent solar cells. A groove is formed between the photoelectrode 10 of a single cell (hereinafter referred to as a single cell A).
[0113]
This groove is formed by scraping the semiconductor electrode 2 of the single cell A by a technique such as laser scribing. The portion of the groove in the vicinity of the sealing material 5 reaches the depth at which the layer of the transparent conductive film 3 of the transparent electrode 1 appears by completely removing the semiconductor electrode 2 portion. Further, in the vicinity of the semiconductor electrode 2 of the single cell A in this groove, the semiconductor electrode 2 portion and the transparent conductive film 3 portion are completely removed to reveal the transparent substrate 4 layer of the transparent electrode 1. It has reached.
[0114]
Further, in the vicinity of the sealing material 5 in the groove, the transparent conductive film 3 of the adjacent photoelectrode 10 and the portions of the semiconductor electrode 2 on the transparent conductive film 3 are not electrically contacted with each other. The edge part formed in the shape of a bowl of the porous body layer PS of the single cell A is inserted between these parts so as to contact the transparent substrate 4 of the transparent electrode 1.
[0115]
Further, in the vicinity of the semiconductor electrode 2 of the single cell A in the groove, that is, in the portion between the porous layer PS of the single cell A and the sealing material 5, the counter electrode CE of the single cell A has a bowl shape. The formed edge portion is inserted so as to be in contact with the transparent conductive film 3 of the transparent electrode 1 of the other single cell.
[0116]
【Example】
EXAMPLES Hereinafter, although an Example and a comparative example are given and it demonstrates in more detail about the dye-sensitized solar cell of this invention, this invention is not limited to these Examples at all.
[0117]
(Example 1)
A photoelectrode having the same configuration as that of the photoelectrode 10 shown in FIG. 1 is prepared by the following procedure, and the same as the dye-sensitized solar cell 20 shown in FIG. 1 except that this photoelectrode is used. Dye-sensitized solar cell having a structure (light receiving surface area: 1 cm²) Was produced.
[0118]
First, except that the temperature of the autoclave was changed to 230 ° C., acetylacetone, ion-exchanged water, a surfactant (Aldrich) according to the method of Barbe et al. Described in Journal of ceramic society (Vol. 80, 3157-3171, 1987). TiO 2 manufactured by the company, trade name: “tritonX”)₂Slurry (TiO2) for forming a semiconductor electrode in which particles (Degussa, trade name: “P25”) are dispersed₂Particle content: 11% by mass, TiO₂The average particle size of the particles: about 10 nm, “Slurry 1”) was prepared.
[0119]
Next, a paste for forming a semiconductor electrode (hereinafter referred to as paste 1) was prepared by adding and mixing polyethylene glycol (manufactured by Wako Pure Chemical Industries, Ltd., number average molecular weight: 2000) as a thickener in slurry 1. . TiO in paste 1₂The mass ratio of particles to polyethylene glycol is TiO₂Particle: Polyethylene glycol was adjusted to be 10: 3.
[0120]
On the other hand, SnO doped with fluorine on the glass substrate 4 (transparent conductive glass)₂Transparent electrode 1 having a conductive film 3 (film thickness: 600 nm) (manufactured by Nippon Sheet Glass Co., Ltd., surface resistance: about 10 Ω / cm)², Thickness; 1 mm). And this SnO₂On the conductive film 3, the above-mentioned paste 1 was applied to a thickness of 100 μm using a doctor blade, and then dried at a temperature of 25 ° C. for 30 minutes.
[0121]
Thereafter, the transparent electrode 1 to which the paste 1 was applied was transferred into an electric furnace and baked in the atmosphere at 450 ° C. for 30 minutes. Next, the transparent electrode 1 was taken out from the electric furnace and cooled. In this way, SnO₂A semiconductor electrode having the same structure as the semiconductor electrode 2 shown in FIG. 1 on the conductive film 3 (light receiving surface area: 4 cm)², Thickness of layer made of semiconductor film; 8 μm, TiO₂Coating amount: 15 g / cm²) Was formed, and a photoelectrode in a state containing no dye (metal complex dye and organic dye) was produced.
[0122]
Then, the pigment | dye was made to adsorb | suck to the back surface of the semiconductor electrode of a photoelectrode as follows. First, as a sensitizing dye, a dye represented by the following formula (I) (Red dye, manufactured by Sololonix, trade name: “N719”) was used, and this was a mixed solvent of ethanol and DMF (mass ratio of ethanol and DMF; Solution dissolved in ethanol: DMF = 1: 1 (sensitizing dye concentration; 3 × 10^-4mol / L) was prepared. Next, the semiconductor electrode was immersed in this solution and left for 12 hours in a dark place at 25 ° C. Next, the semiconductor electrode was taken out from this solution, washed with ethanol, and naturally dried in a dark place. As a result, a sensitizing dye is about 1.2 × 10 6 inside the semiconductor electrode 2.^-7mol / m²The adsorbed photoelectrode 12 was completed.
[0123]
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[0124]
Next, as a counter electrode having the same shape and size as the above-described photoelectrode, a transparent conductive glass electrode (thickness of Pt thin film; 3 nm) on which Pt was deposited by an electron beam deposition method was produced.
[0125]
Further, as an electrolytic solution E, an iodine redox solution containing a boron compound represented by the formula (A1) (tetrabutylammonium iodide concentration; 0.6 mol / L, iodine concentration; 0.1 mol / L, boron compound) Concentration: 0.1 mol / L, solvent: methoxypropionitrile) was prepared.
[0126]
Furthermore, a spacer S (trade name: “High Milan”) manufactured by Mitsui DuPont Polychemical Co., Ltd. having a shape matched to the size of the semiconductor electrode was prepared. Next, as shown in FIG. 3, the photoelectrode 12, the counter electrode CE, and the spacer S were opposed to each other. Then, by using the capillary phenomenon, the space defined by the spacer S, the photoelectrode 12 and the counter electrode CE is filled with the above-described electrolytic solution E from the gap between the spacer S and the photoelectrode 12 or the counter electrode CE. Each member was sealed with an epoxy resin to complete a dye-sensitized solar cell.
[0127]
(Example 2)
As an electrolytic solution E, an iodine redox solution containing a boron compound represented by formula (B1) (tetrabutylammonium iodide concentration; 0.6 mol / L, iodine concentration; 0.1 mol / L, boron compound concentration; 0 0.1 mol / L, solvent; methoxypropionitrile) was prepared. A dye-sensitized solar cell was produced in the same procedure and conditions as in Example 1 except that this electrolytic solution E was used.
[0128]
(Example 3)
As an electrolytic solution E, an iodine redox solution containing a boron compound represented by the formula (A2) (tetrabutylammonium iodide concentration; 0.6 mol / L, iodine concentration; 0.1 mol / L, boron compound concentration; 0 0.1 mol / L, solvent; methoxypropionitrile) was prepared. A dye-sensitized solar cell was produced in the same procedure and conditions as in Example 1 except that this electrolytic solution E was used.
[0129]
Example 4
As an electrolytic solution E, an iodine redox solution containing a boron compound represented by the formula (A3) (tetrabutylammonium iodide concentration; 0.6 mol / L, iodine concentration; 0.1 mol / L, boron compound concentration; 0 0.1 mol / L, solvent; methoxypropionitrile) was prepared. A dye-sensitized solar cell was produced in the same procedure and conditions as in Example 1 except that this electrolytic solution E was used.
[0130]
(Example 5)
As an electrolytic solution E, an iodine redox solution containing a boron compound represented by the formula (D1) (concentration of tetrabutylammonium iodide; 0.6 mol / L, iodine concentration; 0.1 mol / L, concentration of boron compound; 0 0.1 mol / L, solvent; methoxypropionitrile) was prepared. A dye-sensitized solar cell was produced in the same procedure and conditions as in Example 1 except that this electrolytic solution E was used.
[0131]
(Example 6)
As an electrolytic solution E, an iodine redox solution containing a boron compound represented by the formula (C1) (tetrabutylammonium iodide concentration; 0.6 mol / L, iodine concentration; 0.1 mol / L, boron compound concentration; 0 0.1 mol / L, solvent; methoxypropionitrile) was prepared. A dye-sensitized solar cell was produced in the same procedure and conditions as in Example 1 except that this electrolytic solution E was used.
[0132]
(Example 7)
As an electrolytic solution E, an iodine redox solution containing a boron compound represented by the formula (A4) (tetrabutylammonium iodide concentration; 0.6 mol / L, iodine concentration; 0.1 mol / L, boron compound concentration; 0 0.1 mol / L, solvent; methoxypropionitrile) was prepared. A dye-sensitized solar cell was produced in the same procedure and conditions as in Example 1 except that this electrolytic solution E was used.
[0133]
(Example 8)
As an electrolytic solution E, an iodine-based redox solution (concentration of tetrabutylammonium iodide; 0.6 mol / L) containing a dehydration condensate of a compound represented by the formula (G1) (manufactured by Tokyo Chemical Industry Co., Ltd., trade name: “phenylboric acid”) Concentration of iodine; 0.1 mol / L, concentration of the compound represented by the formula (G1); 0.1 mol / L, solvent; methoxypropionitrile). A dye-sensitized solar cell was produced in the same procedure and conditions as in Example 1 except that this electrolytic solution E was used.
[0134]
(Comparative Example 1)
As an electrolytic solution E, an iodine-based redox solution containing no hydrolytic boron compound (concentration of tetrabutylammonium iodide; 0.6 mol / L, concentration of iodine; 0.1 mol / L, solvent; methoxypropionitrile) Was prepared. A dye-sensitized solar cell was produced in the same procedure and conditions as in Example 1 except that this electrolytic solution E was used.
[0135]
[Battery characteristics test 1]
A battery characteristic test was performed according to the following procedure and measurement conditions, and the photoelectric conversion efficiency η of the dye-sensitized solar cells of Examples 1 to 8 and Comparative Example 1 was measured.
[0136]
The battery characteristic test was performed using a solar simulator (trade name; “WXS-85-H type” manufactured by Wacom) and 1000 mW / cm from a xenon lamp light source that passed through an AM filter (AM1.5).²It was performed by irradiating simulated sunlight.
[0137]
First, for each dye-sensitized solar cell, current-voltage characteristics were measured at room temperature using an IV tester, and an open circuit voltage (Voc / V) and a short circuit current (Isc / mA · cm).^-2) And a fill factor (FF) were obtained, and the photoelectric conversion efficiency η [%] at the initial stage of startup was obtained therefrom.
[0138]
Thereafter, each dye-sensitized solar cell is placed in a thermostatic bath maintained at 85 ° C., stored in a light-shielded state and in an open circuit state, and after 360 hours, is taken out of the thermostatic bath and is the same as above at room temperature. The current-voltage characteristics were measured, and the photoelectric conversion efficiency η after 360 hours was obtained. The results are shown in Table 1.
[0139]
[Table 1]

[0140]
As is clear from the results shown in Table 1, the dye-sensitized types of Examples 1 to 8 using an electrolyte containing a boron compound having hydrolytic ability used in the dye-sensitized solar cell of the present invention. The solar cell has excellent photoelectric conversion efficiency even after being stored for a long time under a relatively high temperature operating environment that is most likely to be applied when a dye-sensitized solar cell at 85 ° C. is put into practical use. It was confirmed that it could be almost maintained. On the other hand, in the dye-sensitized solar cell of Comparative Example 1, it was confirmed that the photoelectric conversion efficiency was significantly lowered with the passage of storage time.
[0141]
[Battery characteristics test 2]
A dye-sensitized solar cell of Example 1 and Comparative Example 1 was separately prepared, and a battery characteristic test was performed according to the same procedure and measurement conditions as the above-described battery characteristic test 1 except for the procedure and conditions described below. The photoelectric conversion efficiency η of the dye-sensitized solar cell of Comparative Example 1 was measured.
[0142]
That is, each of the dye-sensitized solar cells of Example 7 and Comparative Example 1 was short-circuited, and the temperature of the electrolytic solution E was kept at 60 ° C., and the above-described 1000 mW / cm²The simulated sunlight was continuously irradiated. The photoelectric conversion efficiency η after 24 hours, 120 hours, and 240 hours from the start of irradiation with pseudo sunlight was measured. The results are shown in Table 2.
[0143]
[Table 2]

[0144]
As is apparent from the results shown in Table 2, after the dye-sensitized solar cell of Example 1 was continuously operated under irradiation of pseudo-sunlight for a long time under an operating environment of 60 ° C. It was also confirmed that excellent photoelectric conversion efficiency can be maintained. On the other hand, compared with the dye-sensitized solar cell of Example 1, the dye-sensitized solar cell of Comparative Example 1 has a significant decrease in photoelectric conversion performance with the passage of pseudo-sunlight irradiation time. confirmed.
[0145]
【The invention's effect】
As described above, according to the present invention, since the antioxidant is contained in the electrolyte, the heat resistance, light resistance and chemical stability of the dye (metal complex dye and organic dye) are easily improved. Therefore, a dye-sensitized solar cell that can obtain excellent photoelectric conversion efficiency over a long period of time can be easily configured.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing the basic configuration of a first embodiment of a dye-sensitized solar cell of the present invention.
FIG. 2 is a schematic cross-sectional view showing a basic configuration of a second embodiment of the dye-sensitized solar cell of the present invention.
3 is a schematic cross-sectional view showing an example when a plurality of dye-sensitized solar cells shown in FIG. 2 are provided.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Transparent electrode, 2 ... Semiconductor electrode, 3 ... Transparent electrically conductive film, 4 ... Transparent substrate, 5 ... Sealing material, 6 ... Transparent substrate, 10 ... Photoelectrode, 20, 30, 40 ... Dye-sensitized solar cell , CE ... counter electrode, E ... electrolyte, F1, F2, F3, ... light receiving surface, F22 ... back surface of the semiconductor electrode 2, L10 ... incident light, S ... spacer, PS ... porous body layer.

Claims (11)

A photoelectrode having a semiconductor electrode having a light receiving surface and a transparent electrode disposed adjacent to the light receiving surface, and a counter electrode;
A dye-sensitized solar cell in which the semiconductor electrode and the counter electrode are arranged to face each other via an electrolyte,
The semiconductor electrode contains a dye,
The electrolyte contains a boron compound having hydrolytic ability,
A dye-sensitized solar cell characterized by The said boron compound is represented by following General formula (1), The dye-sensitized solar cell of Claim 1 characterized by the above-mentioned.

[In Formula (1), n shows the integer of 1-3,
X represents a characteristic group having hydrolytic ability,
R ¹ represents at least one hydrocarbon group selected from the group consisting of an alkyl group, an alkenyl group, an alkynyl group, an allyl group, an aryl group, and a heterocyclic group. ] In the formula (1), at least one hydrogen atom constituting R ¹ is sulfo group, sulfino group, sulfeno group, oxycarbonyl group, haloformyl group, carbamoyl group, hydrazinocarbonyl group, amidino group, cyano group, isocyano group. Group, cyanato group, isocyanato group, thiocyanato group, isothiocyanato group, formyl group, oxo group, thioformyl group, thioxo group, mercapto group, amino group, imino group, hydrazino group, allyloxy group, sulfide group, nitro group, silyl group and The dye-sensitized solar cell according to claim 2, further substituted with at least one substituent selected from the group consisting of halogen atoms. 3. The dye sensitization according to claim 2, wherein the X in the formula (1) is at least one selected from the group consisting of the following general formulas (2) to (5) and a halogen atom. Type solar cell.

[In the formulas (2) to (5), R ¹ has the same meaning as R ¹ in the formula (1),
R ² and R ³ may be the same or different and are each independently selected from the group consisting of a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an allyl group, an aryl group, and a heterocyclic group. At least one
R ⁴ , R ⁵ and R ⁶ may be the same or different, and each independently represents a group consisting of a hydrogen atom, an alkyl group, an alkenyl group, an alkynyl group, an allyl group, an aryl group, and a heterocyclic group. At least one selected from: ] In formulas (2) and (3), at least one hydrogen atom constituting R ¹ is a sulfo group, a sulfino group, a sulfeno group, an oxycarbonyl group, a haloformyl group, a carbamoyl group, a hydrazinocarbonyl group, an amidino group, Cyano group, isocyano group, cyanato group, isocyanato group, thiocyanato group, isothiocyanato group, formyl group, oxo group, thioformyl group, thioxo group, mercapto group, amino group, imino group, hydrazino group, allyloxy group, sulfide group, nitro group The dye-sensitized solar cell according to claim 4, further substituted with at least one substituent selected from the group consisting of silyl group and halogen atom. At least one of R ² and R ³ in the formula (4) is at least one selected from the group consisting of an alkyl group, an alkenyl group, an alkynyl group, an allyl group, an aryl group, and a heterocyclic group. The dye-sensitized solar cell according to claim 4 or 5, wherein the dye-sensitized solar cell is provided. In the formula (4), at least one hydrogen atom constituting at least one of R ² and R ³ is a sulfo group, a sulfino group, a sulfeno group, an oxycarbonyl group, a haloformyl group, a carbamoyl group, a hydrazinocarbonyl group. , Amidino group, cyano group, isocyano group, cyanato group, isocyanato group, thiocyanato group, isothiocyanato group, formyl group, oxo group, thioformyl group, thioxo group, mercapto group, amino group, imino group, hydrazino group, allyloxy group, sulfide The dye-sensitized solar cell according to claim 6, further substituted with at least one substituent selected from the group consisting of a group, a nitro group, a silyl group and a halogen atom. At least one of R ⁴ , R ⁵ and R ^{6 in} the formula (5) is at least selected from the group consisting of an alkyl group, an alkenyl group, an alkynyl group, an allyl group, an aryl group, and a heterocyclic group. It is 1 type, The dye-sensitized solar cell of Claim 4 or 5 characterized by the above-mentioned. In formula (5), at least one hydrogen atom constituting at least one of R ⁴ , R ⁵ and R ⁶ is a sulfo group, a sulfino group, a sulfeno group, an oxycarbonyl group, a haloformyl group, a carbamoyl group, Hydrazinocarbonyl group, amidino group, cyano group, isocyano group, cyanato group, isocyanato group, thiocyanato group, isothiocyanato group, formyl group, oxo group, thioformyl group, thioxo group, mercapto group, amino group, imino group, hydrazino group, The dye-sensitized solar cell according to claim 8, further substituted with at least one substituent selected from the group consisting of an allyloxy group, a sulfide group, a nitro group, a silyl group, and a halogen atom. . 2. The dye-sensitized solar according to claim 1, wherein the boron compound is a reaction product obtained by subjecting two or more compounds represented by the following general formula (6) to an intermolecular dehydration reaction. battery.

[In Formula (6), m shows the integer of 1-3,
R ¹ represents at least one hydrocarbon group selected from the group consisting of an alkyl group, an alkenyl group, an alkynyl group, an allyl group, an aryl group, and a heterocyclic group. ] In the formula (6), at least one hydrogen atom constituting R ¹ is a sulfo group, a sulfino group, a sulfeno group, an oxycarbonyl group, a haloformyl group, a carbamoyl group, a hydrazinocarbonyl group, an amidino group, a cyano group, an isocyano group. Group, cyanato group, isocyanato group, thiocyanato group, isothiocyanato group, formyl group, oxo group, thioformyl group, thioxo group, mercapto group, amino group, imino group, hydrazino group, allyloxy group, sulfide group, nitro group, silyl group and The dye-sensitized solar cell according to claim 10, further substituted with at least one substituent selected from the group consisting of halogen atoms.

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