200945605 六、發明說明： 【發明所屬之技術領域】 [0001] 本發明係有關於太陽電池，尤關於具備於透 複數之發電層的構造之太陽電池。 A W極上堆疊有 【先前技術】 【0002】 〇 之-===使用成為地球暖化之可能的原因 人t 種乾淨又可謂無窮的能源而因此引 【0003】献丨自场能取得電力之各娜摘太陽電池。 芦的:i 池’已有—種薄膜太陽電池，其為1型半導體 型（如P型）半導體層以及逆導電型（如nBACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solar cell, and more particularly to a solar cell having a structure of a power generation layer having a plurality of transmissions. AW pole stacking [Prior Art] [0002] 〇之-=== Use of the potential for global warming is a kind of clean and infinite energy source. Therefore, [0003] Na picked the solar battery. Reed: i pool 'has been a type of thin film solar cell, which is a type 1 semiconductor type (such as P type) semiconductor layer and a reverse conductivity type (such as n
Q ί ίϊ等各種+導體以形成，並且使用如Si、SiC、Ge、SiGe等 t〇〇〇4r 導體層，也已絲所週知。 有微池，如於專利文獻1中已揭露具備含 雷％。w # u f見叫_Si)層的ρώ型異晶質薄膜太陽 發電層之pHH的薄膜域電池具有下述構造：在形成 由非曰功扯广曰中由s有微晶相的半導體層形成p層’ Si 形成1，並在前述P層與i層之間設置一 介面房兔巧層相較於P層，其能帶間隙（band-gap)較寬’該 抑制i照農度陆具備如上述構造的太陽電池’可 疋雀化，同時，能提高效率。 200945605 « ) ‘ [0005] 另於專利文獻2中揭露—種太陽 擴散所造成的介面特性劣化，並且高轉換效二中因熱 文獻2中所揭露之太陽魏，其^^^的^電池。專利 由含微晶相之非晶矽膜（AC_Si天電層的Ρ«ι層中，分別 由含微晶層的非晶質半導體層，和二MP，及n型半導體層，並且 再者，專娜2也提及轉體層。 置有複數層之介面半導體層的構t在^導體層之間設 體層側的介面半導體之摻雜物在f利文獻2中，將i型半導 介面半導體層中的摻雜物添加^t 半導體侧的 ❹雌合蚊崎型半 【_#述構造的太陽魏可_介面之劣化。 ==公開公報特開2〇01·168354號 獻】日本專利公開公報特開2〇〇3_8〇38號 【發明内容】 ❹ 鳘jj所欲解決之P4~gi 【_】 以供應將來有^慮將使用太陽電池， 替代石油等化石燃料而且認為，實際上也無法取得足以 [00093 能製試算’如果改善轉換效率的同時， 相當於每年的電消=之=陽電池’發現則由太陽電池可取得 【0010】 池，=====繼提供太陽電 200945605 解決問題之方式 【0011】 依本發明之第一態樣，提供一種太陽電池，包含：發電 5於，-及第二電極之間堆紐此具有不同光吸收帶的電池 (cell)而成，其中，前述第一電極為透明電極，並且前述第二 發電層之間’設置有-金屬層，其由接觸電阻小於g 二，及前述發電層之間的接觸電阻之金屬所形成。 疋 依本發明之第二態樣，提供一種太陽電池，其中，第一熊 ❾其功函數小於前述金4層所接觸的發^層 【0013】 ^發明之第三態樣，提供如第二態樣之太陽電池，其中， 月'J述金屬層所接觸的發電層，係n型鍺。 【0014】 兄、十明之第四態樣，提供如第二態樣之太陽電池，其中， 7 = 2層所接觸之發電層，係n型鍺，且前述金屬層 組中^遥二)、錳(Mn)、錯(Zr)以及釔⑺所組成的群 、、r中選擇的至少一種金屬或其合金所形成。 鮮 Q 【0015】 之明之第五態樣’提供如第—至第四態樣中，任-態樣 (d〇Ub1^ 【0016】 前述供如第五態樣中之太陽電池，其中， 【0017】 前述3嘗J供如第六態樣的太陽電池’其中’ 構造之雜I構雙電構造包含：具有由微抑所形成之pin - 、，和具有由微晶鍺形成之pin構造的底電池。 200945605 【_】 ▲，本發明之第八態樣，提供如第五態樣的太陽電池，其 刖述三電池構造具有9層構造。 【0019】 且古ΐ本發明之第九態樣’提供如第八態樣的太陽電池’其中’ 刖述第9層構造之三電池構造，具有將職池、巾間電池以 及底電池依序堆疊在前述第一電極上之構造。 【0020】 、依本發明之第十態樣’提供如第九態樣的太陽電池，其中前 ❹ f頂電池具備鱗㈣所形成之pin船：，*述巾㈣池具備由微 晶矽鍺所形成之pin構造，加上，前述底電池具備由微晶鍺所形 之pin構造。 發明效果 【0021】 依本發明之太陽電池，其包含具有不同光吸收能帶之發電 層，同時，作為電極，將其接觸電阻為小的金屬層配置於電極的 底層（下地層）’藉此’提高轉換效率高達約2〇0/〇。 【實施方式】 Q 以下將參照圖式詳細說明依本發明的較佳實施形態。 [0024] 利用圖1所示的光波長與光子數量之間的關係，將本發明之 原理加以說明。做為入射光In，入射的太陽光具有由5〇〇nm以下 之紫外線區域至2500nm以上之遠紅外線的廣範圍的波長。如可在 廣大範圍内吸收此入射光In，並且轉換成電能，則可取得轉換效 率頗高之太陽電池。 ' 【0025】 在此，如曲線Aa所示，將對500nm以下之光波長至可見光 區域的光波長顯示有高吸收係數之材料（如非晶矽），和如曲線 Am所示’對含有lOOOnm的光波長顯示有高吸收係數之材料（如 200945605 微晶石夕錯⑽-SCe))予以組合，可構成光吸收係數極為高之太陽 ，池。加上，如曲線Ag所示，將相較於微晶矽鍺，相對長波長顯 示高的，吸收係數之材料（如微晶鍺⑽_Ge))予以組合，藉此可 構成太1%光之未被吸收部份Na極為少的太陽電池。 [0026】 基於上述原理’於本發明中討論，曲線Aa、Am、Ag的三種 吸收特性中’至少能實現如曲線Aa、Am的吸收特性之太陽電池， 同時，也討論各材料之產生電壓。 [0027】 加上，於本發明中，發現如將夾持發電層之電極材料加以改 〇善’則可構成轉換效率高的太陽電池。 【0028】 參照圖2，表示依本發明的具有6層構造之太陽電池的一例 子。圖示的太陽電池包含：於玻璃基板21上由Zn〇等形成而 明的第一電極（TCO,亦即 Transparent Conducting Oxide) 23、設 電極23上的6層構造之發電層25、形成於發電層25的 底金屬層27以及A1或Ag所形成的第二電極29。 【0029】 戶斤二Πί的if電池之發電層25，包含：將具備微晶石夕 ❹，ίΐΓ構&之了頁電池251 ’和具備微晶錯所形成之Pin構造 之底電池252堆疊的構造。在此，頂電池251 另一方面，底電池252具有0.5仰的厚度。在此有頂^池·^度 陽光入射的透明第一電極23側的電池，而配置“ 第一電極23侧的電池稱之為底電池252。 【0030】 a Ϊ上’第二電極29之底金屬層27相對錯形成歐姆接觸，且 由相較於Α1的接觸電阻為小之金屬（如鎂） 【0031】 乂 如圖示構造的太陽電池，其形成於大小為2J6mx2 板上，並且具有19.8%之轉換效率。 心娄 200945605 · ' 【0032】 另外，底金屬層27 2料的電子親和力之絕對選擇其功函數小於形成底電池 在圖2所不的構造中，梦一 一方面，底金屬層27的厚度4二增強反射之功能。另 上述底金屬層27的材料，除；太陽光的厚度者為佳。 群财選擇的至少mm"?給、猛、錯以及紀 之中間電池25im及微晶鍺所形成的i構 2，的ριη構& 而成之構造。 ㈣成的Pln構k之底電池25c所堆疊 【0035】 前述頂電池25a、中㈤電池25b以及底電、池25c之厚度，分別 為l.O/mi、3.5/mi及0.5卿’因此，發電層25的整體厚度係 如此以來’使9層構造的太陽電池可具有高達如 Q 且可大型化以及可量產化。 f 【0036】 參照圖4顯示具有9層構造，且具有相較圖3所示的太陽電 池為薄的薄膜構造之太陽電池。其頂電池25a、中間電池25b以及 底電池25c之膜構造’如同圖3，係分別由非晶矽所形成的pin構 造、微晶珍諸所形成的pin構造以及微晶錯所形成的pin構造以形 成。 【0037】 加上，頂電池25a、中間電池25b以及底電池25c的厚度分別 係0·5μιη、Ι.ΐμπι以及〇.4/«η。如此構造的太陽電池的轉換效率為 19.8%。 8 200945605 · 【0038】 【〇〇5Γ參照圖5將本發明的實施例1加以說明。 明池之剖面圖，由圖得知，於玻璃基 Ϊ = _( )之氧化辞所形成之透明第一電極23成 [0040] 已形成的第一電極23上，脾η;,丨4 Q Q 型非晶矽層4 (膜厚〇.5卿)、n型非曰曰:夕層3 (严2〇?)、1 成長，以形成頂電池25a。 H石夕層5 (膜厚2〇nm)依序 ❹【0041】 ，著’將P型微晶魏層6 (膜厚5〇腿)、微晶石夕錯層 fm晶補層8 (财d鱗錄，以形成中 【0042] 加上’上述η型微晶矽鍺層8上，將 5==、微晶鍺層Π)(膜厚α4μιη)、η型微晶錯層u (膜厚H 依序成長，以形成底電池25c。 [0043] ❹【(χ^ί形祕層27 (膜厚Μ她層29 (膜厚_)。 接著，成長SiN膜34 (膜厚5jam)。於SiN層34上介由 劑層35貼付散熱用金屬板36。 著 【0045】 參照圖6，將本發明的實施例2之太陽電池加以說明。圖 :由透明電極（TC〇)形成之第—電極23、形成於前^ 電極23上之p型半導體層251a、由含有微晶矽之非晶質矽 質矽，Mc-Si)所形成之i型半導體層253a以及^型半導體層252/。 力口上’其上方更具備：p型半導體層25卜含有微晶的非日^ C/xc-Ge)所形成之i型半導體層253a以及^型半導體層252。加 200945605 成依本發明之金屬層30，再者，於前述金屬居30 ΪΓ又ίίί1形成的第二電極29。如參照圖2加以說明，金θ屬声 30，係考慮了與作為底㉟的η型半導體| 252 屬二 由既定金屬所形成的。 π力函數，而 【0046】 作為底層之η型半導體層252,如前述由η型微晶鍺 i金屬層30則由鎂、給、經、錯以及紀所組成之群组中選 擇的至少一種金屬或其合成即可。 砰、，且肀選 【0047】 〇 ❹ 南上：ί製造具上述構造的太陽電池所使用的成膜以及蝕刻 ^備，如姻旋轉雜績裝置，則可整體設備大幅小型 [0048] j如，利用磁控濺鍍裝置連續地進行成膜，則可將 多層膜的整個設舒以縮小。例如，在相隨室内，利雌g 控雜裝置以連續地成長絲屬層27彳4二電極29，職 ===個別成長底金屬層27和第二電極29之情況，可將設 產業上利用性 [0049] =述實施例’僅對太陽電池加以說明，但 於一般光電轉換元件。 j』週用 【圖式簡單說明】 【0022】 圖1表，太陽光譜，㈣說明本發明之原理。 ^3#^m^6層構造之太陽電池的-例子之示意圖。 9層觀之域電池關子之示意圖。 圖5矣二佑太恭^不之太陽電池予以薄膜化的示意圖。 不發月之第-實施例的太陽電池之剖面圖。 200945605 圖6表示依本發明之第二實施例的太陽電池之剖面圖。 【主要元件符號說明】 【0023】 3 p型非晶矽層 4 i型非晶矽層 5 η型非晶矽層 6 ρ型微晶矽鍺層 7 微晶矽鍺層 8 η型微晶矽鍺層It is also known that various + conductors such as Q ί ϊ are formed and a t 〇〇〇 4r conductor layer such as Si, SiC, Ge, SiGe or the like is used. There is a microcell, as disclosed in Patent Document 1, which has a % of Ray. The pHH thin film domain cell of the ρώ type heteromorphic thin film solar power generation layer of w# uf is called _Si) layer has the following structure: formed by a semiconductor layer having a microcrystalline phase in sigma The p layer 'Si forms 1 and an intervening rabbit layer is disposed between the P layer and the i layer, and the band-gap is wider than the P layer. The solar cell constructed as described above can be smashed, and at the same time, efficiency can be improved. 200945605 « ) ‘ [0005] It is disclosed in Patent Document 2 that the interface characteristics caused by the diffusion of the sun are deteriorated, and the high conversion efficiency is due to the solar radiation disclosed in the heat document 2, and the battery of the ^^^. The patent consists of an amorphous tantalum film containing a microcrystalline phase (in the Ρ« layer of the AC_Si sky layer, respectively, an amorphous semiconductor layer containing a microcrystalline layer, and a second MP, and an n-type semiconductor layer, and further, The conductor layer is also referred to as a transfer layer. The interface semiconductor layer having a plurality of layers is provided with a dopant of an interface semiconductor on the body layer side between the conductor layers. In the document 2, an i-type semiconductor semiconductor is used. The dopant in the layer is added to the semiconductor side of the ❹ 合 合 型 型 半 半 _ _ 劣化 。 。 。 。 。 。 。 。 。 】 】 】 】 】 】 】 】 】 】 】 】 】 】 】 】 】 】 】 】 】 】 】 】 】 】 】 Bulletin Specials 2〇〇3_8〇38号 [Content of the Invention] P 鳘jj wants to solve the P4~gi [_] In the future, there will be solar cells used instead of fossil fuels such as petroleum, and it is actually impossible to Obtained enough [00093 can make a trial calculation] If the conversion efficiency is improved, the equivalent of the annual electricity consumption = the = positive battery' is found by the solar cell [0010] pool, ===== following the provision of solar power 200945605 Way of Problem [0011] According to the first aspect of the present invention, a The anode battery comprises: a power generation 5, and a battery having a different light absorption band between the second electrodes, wherein the first electrode is a transparent electrode, and the second power generation layer is between 'providing a metal layer formed of a metal having a contact resistance smaller than g 2 and a contact resistance between the foregoing power generation layers. According to a second aspect of the present invention, a solar cell is provided, wherein the first bear The work function is smaller than the third layer of the invention in which the gold layer 4 is contacted. The third aspect of the invention provides a solar cell according to the second aspect, wherein the power layer contacted by the metal layer is [0014] The fourth aspect of the brother, the tenth, provides a solar cell as in the second aspect, wherein the power generation layer contacted by 7 = 2 layers is an n-type germanium, and the aforementioned metal layer group is ^ It is formed by a group consisting of manganese (Mn), dysprosium (Zr) and cerium (7), at least one metal selected from r or an alloy thereof. Fresh Q [0015] The fifth aspect of the invention provides a solar cell as in the fifth aspect, as in the first to fourth aspects, (d〇Ub1^ [0016] The above-mentioned 3 taste J is provided for the solar cell of the sixth aspect, wherein the hetero-structure of the hetero-structure consists of: a pin-shaped body formed by micro-suppression, and a pin structure formed of microcrystalline germanium. Bottom battery. 200945605 [_] ▲, according to an eighth aspect of the present invention, a solar cell according to a fifth aspect is provided, wherein the three-cell structure has a nine-layer structure. [0019] and the ninth state of the present invention The invention provides a solar cell as in the eighth aspect, wherein the three-cell structure of the ninth layer structure is described, and has a structure in which a cell, an inter-cell battery, and a bottom cell are sequentially stacked on the first electrode. According to the tenth aspect of the present invention, a solar cell according to the ninth aspect is provided, wherein the front ❹ f top battery has a pin boat formed by the scale (four): the *the towel (four) pool is formed by the microcrystalline crucible The pin structure, in addition, the bottom battery has a pin structure formed by a microcrystalline crucible. [0021] The solar cell according to the present invention comprises a power generation layer having different light absorption bands, and at the same time, as an electrode, a metal layer having a small contact resistance is disposed on the bottom layer (lower layer) of the electrode. The conversion efficiency is improved by about 2 〇 0 / 〇. [Embodiment] Q Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the drawings. [0024] The relationship between the wavelength of light and the number of photons shown in FIG. 1 is utilized. The principle of the present invention will be described. As the incident light In, the incident sunlight has a wide range of wavelengths from an ultraviolet region of 5 〇〇 nm or less to a far infrared ray of 2500 nm or more. Such absorption can be absorbed over a wide range. When the light In is converted into electric energy, a solar cell having a high conversion efficiency can be obtained. ' [0025] Here, as shown by the curve Aa, a high absorption coefficient is shown for the wavelength of light having a wavelength of light of 500 nm or less to the visible light region. The material (such as amorphous germanium), and as shown by the curve Am 'combination of materials with a high absorption coefficient of light wavelengths containing lOOOnm (such as 200945605 microcrystalline stone (10)-SCe)) It may constitute a very high optical absorption coefficient of the sun, pool. In addition, as shown by the curve Ag, a relatively high wavelength, absorption coefficient material (such as microcrystalline germanium (10)_Ge) is combined with the microcrystalline germanium, thereby forming too much light of 1%. A solar cell with a very small amount of Na absorbed. Based on the above principle, as discussed in the present invention, among the three absorption characteristics of the curves Aa, Am, and Ag, solar cells having at least the absorption characteristics of the curves Aa and Am can be realized, and the voltages of the respective materials are also discussed. Further, in the present invention, it has been found that a solar cell having a high conversion efficiency can be constructed by modifying the electrode material of the power generation layer. Referring to Fig. 2, an example of a solar cell having a six-layer structure according to the present invention will be described. The solar cell shown in the figure includes a first electrode (TCO, that is, a Transparent Conducting Oxide) 23 which is formed of Zn or the like on the glass substrate 21, and a power generation layer 25 having a six-layer structure on the electrode 23, which is formed in power generation. The bottom metal layer 27 of the layer 25 and the second electrode 29 formed by A1 or Ag. [0029] The power generation layer 25 of the if battery of the battery includes: a battery cell 251 having a microcrystalline stone ❹ ❹, a ΐΓ & amp & and a bottom battery 252 having a Pin structure formed by micromorphism Construction. Here, the top battery 251, on the other hand, the bottom battery 252 has a thickness of 0.5 angstrom. Here, there is a battery on the side of the transparent first electrode 23 on which the sunlight is incident, and the battery on the side of the first electrode 23 is referred to as a bottom battery 252. [0030] a "on the second electrode 29" The bottom metal layer 27 is erroneously formed in an ohmic contact, and is made of a metal having a small contact resistance compared to Α1 (such as magnesium). [0031] A solar cell constructed as shown in the drawing is formed on a board having a size of 2J6mx2 and having 19.8% conversion efficiency. 娄200945605 · ' [0032] In addition, the absolute selection of the electron affinity of the bottom metal layer 27 2 is less than the formation of the bottom cell in the structure of Figure 2, the dream, the bottom The thickness of the metal layer 27 is two to enhance the function of reflection. The material of the bottom metal layer 27 is better than the thickness of the sunlight. The at least mm" of the group, the fierce, the wrong, and the intermediate battery 25im and The structure of the structure of the structure of the structure of the structure of the structure of the structure of the structure of the structure of the structure of the structure of the structure of the structure of the substrate of the structure of the substrate of the structure of the substrate of the crystal cell 25c [0035] the above-mentioned top cell 25a, the middle (five) battery 25b and the bottom electricity, pool 25c The thickness is 10/mi, 3.5/mi and 0.5 'Therefore, the overall thickness of the power generation layer 25 is such that the solar cell of the nine-layer structure can have as high as Q and can be enlarged and mass-produced. f [0036] Referring to FIG. 4, it has a 9-layer structure and has A solar cell having a thin film structure compared to the solar cell shown in Fig. 3. The film structure of the top cell 25a, the intermediate cell 25b, and the bottom cell 25c is the same as that of Fig. 3, which is a pin structure formed of amorphous germanium, The pin structure formed by the microcrystals and the pin structure formed by the microcrystals are formed. [0037] The thicknesses of the top cell 25a, the intermediate cell 25b, and the bottom cell 25c are respectively 0. 5 μm, Ι.ΐμπι, and 〇.4/«η. The conversion efficiency of the thus constructed solar cell is 19.8%. 8 200945605 · [0038] [〇〇5Γ] The embodiment 1 of the present invention will be described with reference to Fig. 5. It is understood that the transparent first electrode 23 formed by the oxidation of the glass base Ϊ = _( ) is formed on the first electrode 23 which has been formed, the spleen η, and the 丨 4 QQ type amorphous ruthenium layer 4 (film thickness) 〇.5卿), n-type non-曰曰: 夕层3 (strict 2〇?), 1 growth, to Forming the top cell 25a. H Shi Xi layer 5 (film thickness 2 〇 nm) sequentially ❹ [0041], 'P-type microcrystalline Wei layer 6 (film thickness 5 〇 leg), microcrystalline 夕 错 层 fm crystal Replenishment layer 8 (figure d scale recording to form medium [0042] plus 'the above-mentioned n-type microcrystalline germanium layer 8, 5==, microcrystalline germanium layer Π) (film thickness α4μιη), η-type crystallite The staggered layer u (the film thickness H is sequentially grown to form the bottom battery 25c). [0043] ❹ [( χ ί 形 形 27 layer 27 (film thickness Μ her layer 29 (film thickness _). Next, the SiN film 34 (film thickness 5jam) is grown. The heat dissipation layer is applied to the SiN layer 34 via the agent layer 35 The solar cell of the second embodiment of the present invention will be described with reference to Fig. 6. Fig.: The first electrode 23 formed of a transparent electrode (TC〇) is formed on the front electrode 23. The p-type semiconductor layer 251a, the i-type semiconductor layer 253a and the ?-type semiconductor layer 252/ formed of amorphous enamel enamel containing microcrystalline germanium, Mc-Si). The layer 25 includes an i-type semiconductor layer 253a and a semiconductor layer 252 formed of a microcrystalline non-infrared C/xc-Ge. Adding 200945605 to the metal layer 30 of the present invention, and further, the second electrode 29 formed by the aforementioned metal is 30 ΪΓ and ίίί1. As described with reference to Fig. 2, the gold θ is an acoustic 30, and is considered to be formed of a predetermined metal from the n-type semiconductor | 252 as the bottom 35. π force function, and [0046] as the bottom layer of the n-type semiconductor layer 252, as described above, at least one selected from the group consisting of magnesium, donor, warp, error, and quaternary Metal or its synthesis can be.砰,, and select [0047] 〇❹ South: ί 制作 制作 制作 制作 制作 制作 制作 制作 制作 制作 制作 制作 制作 制作 制作 制作 制作 制作 制作 制作 制作 制作 制作 制作 制作 制作 制作 制作 制作 制作 制作 制作 制作 制作 制作 制作 制作 制作 制作 制作 制作 制作 制作 制作 制作By continuously forming a film by a magnetron sputtering apparatus, the entire layer of the multilayer film can be reduced. For example, in the same room, the female g-doping device continuously grows the silk layer 27彳4 two electrodes 29, and the position === individual growth of the bottom metal layer 27 and the second electrode 29 can be industrially Utilities [0049] The above-described embodiment describes only solar cells, but in general photoelectric conversion elements. j 』周周 [Simplified illustration of the schema] [0022] Figure 1, table, solar spectrum, (d) illustrates the principle of the invention. ^3#^m^6-layer structure of the solar cell - an example of the example. A schematic diagram of the battery compartment of the 9-layer view. Figure 5 is a schematic diagram of the thinning of the solar cell. A cross-sectional view of a solar cell of the first embodiment of the present invention. 200945605 Figure 6 is a cross-sectional view showing a solar cell according to a second embodiment of the present invention. [Main component symbol description] [0023] 3 p-type amorphous germanium layer 4 i-type amorphous germanium layer 5 n-type amorphous germanium layer 6 p-type microcrystalline germanium layer 7 microcrystalline germanium layer 8 n-type microcrystalline germanium Layer
❹ 9 ρ型微晶鍺層 10微晶鍺層 11 η型微晶鍺層 21玻璃基板 23第一電極（透明導電膜） 25發電層 27、30底層金屬層 29 第二電極 251頂電池 252底電池 25a頂電池 25b中間電池 25c底電池 34 SiN 層 35粘著劑層 36散熱用金屬板 251a ρ型半導體層 252a η型半導體層 253、253a i型半導體層 11❹ 9 ρ-type microcrystalline germanium layer 10 microcrystalline germanium layer 11 n-type microcrystalline germanium layer 21 glass substrate 23 first electrode (transparent conductive film) 25 power generation layer 27, 30 underlying metal layer 29 second electrode 251 top cell 252 bottom Battery 25a top battery 25b intermediate battery 25c bottom battery 34 SiN layer 35 adhesive layer 36 heat dissipation metal plate 251a p-type semiconductor layer 252a n-type semiconductor layer 253, 253a i-type semiconductor layer 11