201227978 六、發明說明： 【發明所屬之技術領域】 本發明係關於一種薄膜太陽能電池結構，該結構可使同一道入射光在 太陽能電池中進行多次反射並造成多次光伏轉換，從而產生更多的電 能，以提高太陽能電池的轉換效率。 【先前技術】 太陽能電池係一將太陽能轉換成電能的設備。若以材料來區分，可以 區分為矽、化合物半導體、染料或有機太陽能電池。若以結構來做區分， 大致可以區分為結晶型太陽能電池與薄膜太陽能電池。以矽太陽能電 池而S，通常單晶石夕與多晶石夕太陽能電池式屬於結晶型太陽能電池而 非晶矽、微晶矽太陽能電池則是屬於薄膜太陽能電池。 傳統太陽能電池所使用的光吸收層、第一導電層與第二導電層為平面 的疊構，從第二導電層反射的光離開太陽能電池就無法再利用。有些 已知技術提出增加使光停留在光吸收層機率的方法。例如有已知技術 利用粗糙的第二導電層改變反射光的角度使部分反射光到了玻璃空氣 介面再全反射回到太陽能電池，但不是所有的光都會全反射。也有些 已知技術做出紋路起伏的第一導電層、光吸收層以及第二導電層的疊 構(在本文中稱為光—伏轉換結構），以改變光在光伏轉換層中的行進 路線而增加反射光在玻璃-空氣介面時再反射回光-伏轉換層的比率， 但這樣也會增加光在行經第一導電層與光吸收層間介面時的反射損失。 201227978 而且如上所述，這些已知技術只能增加使光停留在光吸收層機率，仍 有部分光會直接離開太陽能電池。 【發明内容】 本發明係垂直截面為類似鋸齒狀起伏的非平面薄膜光_伏轉換結構，可 使幾乎所有的垂直入射光在非平面結構間形成數次反射，從而造成數 次光-伏轉換而產生較多的電能，提升轉換效率。與前段所提到的已知 技術的最大不同處在於:第一，本發明之非平面起伏的尺度比光_伏轉 換結構的厚度大3倍以上。如此，入射光在經過一次光_伏轉換後幾乎 所有剩餘的光會被第二導電層反射至非平面起伏的對面某處並再次進 行光-伏轉換，而且會持續反射直到離開非平面起伏的區域。反觀前述 已知技術的紋路，其起伏的尺度小於光-伏轉換結構的厚度，主要目 的在於以小尺度起伏造成散射的效果，將入射光與被第二導電層反射 的光散射成許多不同的行進方向，以增加光在光_伏轉換結構内反覆 反射的機率。但是整體而言仍有部分光會直接離開或是只經過一、二次 反射就離開光-伏轉換結構。第二，本發明之非平面起伏的傾斜角度較 大。基本上所有的非平面太陽能電池都會面臨光在行經第一導電層與 光吸收層間介面時會有反射損失增加的問題。目為具有較傾斜的角度， 在本發明裡的所謂『反射損失』不會如同在已知技術裡般直接離開太陽 能電池是反射至非平面起伏麟面某處並再錢行光伏轉換， 如果該『某處』再次出現部分『反射損失』則會持續前述的動作直到最後 201227978 剩餘的『反射損失』離開非平面起伏的區域。不過由於數次的再利用， 最後剩餘的『反射損失』應該可以減到最少。 【實施方式】 請參考圖1A的垂直截面圖，本發明係關於一種可用於薄膜太陽能電 池(例如矽4匕合物半導體、染料敏化太陽能電池等），而入射光可以在 其非平面光-伏轉換結構間進行數次反射以增加轉換效率的薄膜太陽 能電池結構100，該電池結構100包括由至少一層的非平面光吸收層 103、一至少部分透明的第一導電層1〇2、一可為至少部分透明也可為完 全反光的第一導電層104所疊構而成的光-伏轉換結構以及可選擇性地 增加的一保護層101與一基底105。其中該第一導電層1〇2與該光吸收 層103 —起形成非平面的起伏，且其在遠離該光吸收層1〇3的那一側， 可以選擇性地增加保護層或抗反射的處理；此外，該第一導電層 102在與該光吸收層1〇3間的介面可以選擇性地增導電的加緩衝層來 避免轉換效率受影響，例如CIS/CIGS所使用的緩衝層❶該保護層101 可使用玻璃、透明壓克力、透明塑膠或其他透明的材質，其在遠離該第 一導電層102的那一側，可以與該第一導電層1〇2 一起形成非平面的 起伏，也可以形成如圖1所顯示的平面，且可以選擇性地增加抗反射 的處理。該第二導電層104在遠離該光吸收層1〇3的那一侧，可以與該 光吸收層103 —起形成非平面的起伏，也可以形成如圖1所顯示的平 面；而且當該電池結構1〇〇使用基底(substrate)結構的製程(以第二導電 201227978 層104為基底或直接以基底l〇5為基底，開始向上沉積圖1的其他層 面)時，可在第二導電層104在遠離該光吸收層103的那一側選擇性地 增加玻璃、不鏽鋼、壓克力、塑膠或其他材質的基底105，如果使用 superstrate結構的製程(以保護層1〇1為基底，開始反向沉積圖1的其 他層面)則不必然需要基底105。若有需要，第二導電層104與基底105 之間可選擇性地增加一層絕緣薄膜。該光吸收層103為薄膜太陽能電池 進行光-伏轉換，也就是吸收光而產生電能的地方。舉例而言，如果將 本發明的結構應用於傳統非晶矽薄膜太陽能電池，該光吸收層1〇3就 是由P型非晶矽薄膜，I型非晶矽薄膜與N型非晶矽薄膜疊構而成。而 如果將本發明的結構應用於CIS/CIGS太陽能電池，則該光吸收層1〇3 就是由 P 型 CuInSeV Cu(In，Ga)Se2 與 N 型 CuInSe〆 Cu(In，Ga)Se2 薄膜疊 構而成。由於上述之結構為習知技術，因此不再贅述。此外，依據本發 明之一較佳具體實例，參見圖1A，該非平面光吸收層1〇3之峰與谷的 高度差t為其厚度d的3倍以上，且傾斜角度須不小於45度（圖1B 所示者為75度）+此，則入射光在經過一次光-伏轉換後，幾乎所有 剩餘的光會被該第二導電層104反射至非平面起伏的對面某處並再次 進行光-伏轉換’而且會持續反射直到離開非平面起伏的區域。 第一導電層102可以是單一導電材料，也可由數種導電材料形成。此外， 第一導電層102可依需求(例如大面積的太陽能電池需要降低表層電極 的串聯電阻）增加由電阻值較低的材質（通常是金屬）所形成的電極 201227978 (electrode finger and bus)。由於上述之應用為習知技術，因此不 再贅述。 第二導電層104可以是單一導電材料，也可由數種導電材料形成你據 本發明之一較佳具體實例，如果要對轉換效率做最佳化，第二導電層 104必須是完全反光的電極。而如果依使用上的特殊需求，例如建築物 上需要透光的太陽能電池時，第二導電層1〇4就可選用至少部分透明 的材質。也就是說，本發明可以依需求來選用不同反射率的第二導電 層104 ’而其反射率的範圍可從20%到100%。因為在非平面光-伏轉換 結構間進行數次反射是增加轉換效率的主要因素，第二導電層104不 建議採用反射率低於20%的材料，反射率在40%以上是比較好的，最 好是在60%以上。 當第二導電層1〇4為完全反光的電極時’可將進行過光_伏轉換反應而 剩餘的入射光反射至薄膜太陽能電池的另一處，再次進行光伏轉換而 產生電能。一道垂直入射光能產生光-伏轉換的次數與該入射光在第二 導電層104上的接觸點之切面與平面的夾角(傾斜角度)有關。當該第二 導電層104與光吸收層1〇3相鄰那一面的各傾斜面之傾斜角度大於45 度時’每一道垂直入射光都可造成數次光_伏轉換而產生較多的電能， 提升轉換效率。舉例而言，當傾斜角度為75度時，請參考圖m，第二 導電層104可將垂直入射光1〇6進行六次反射，也就是有六次與光吸 收層103反應並產生電能的機會。而當傾斜角度為6〇度時，每一道垂 201227978 直入射光可造成三次反射，也就是有三次與光吸收層反應並產生電能 的機會°同理’當傾斜角度為45度時，每一道垂直入射光可造成二次 反射’也就是有二次與光吸收層反應並產生電能的機會。若傾斜角度 小於45度’則部分甚至所有垂直入射光只有一次光吸收層反應並產生 電能的機會。因此’傾斜角度小於45度是不被建議的(因製程而導致小 比例的波峰與波谷傾斜小於45度是可接受的）；50度(含)以上是比較 建議的；最好是在60度(含)以上。此外，如圖1B所顯示的，兩個相對 的傾斜面，其傾斜角度相同(75度）；然而’兩個相對的傾斜面也可以 採用不相同的角度。兩個相鄰的波谷可以位於不同的水平面上；兩個 相鄰的波峰也可以是不同的高度。 有時候依使用上的需求，例如使用在建築物上時，太陽能電池被要求 是部分透光的，而第二導電層204就必須使用至少部分透明的材質。此 時，照射在第二導電層204上的入射光除了會產生反射光外，還會有 透射光。比起使用完全反光的第二導電層的狀況，反射光的強度會減 弱啦是由於有透射光，請參考圖2的圓圈標示處，這種結構對於較傾 斜的入射光(例如206、207)卻可提供數次與光吸收層2〇3反應而產生電 能的機會。 當使用數層光吸收層時，可以選擇由數層光譜吸收率涵蓋不同範圍的 光吸收層疊構而成，以增加對入射光譜的使用率。而各光吸收層間可 以選擇增加導電的緩衝層。 201227978 此外第—導電層與光吸收層相鄰那—面的傾斜角度（亦即該非平面 光吸收層103之傾斜角度）也可以是隨著在該傾斜面上的位置不同而 變化的，例如漸變式的。圖3A是漸變式結構的其中-種實施方式，在 本發明中稱為漸進式與大致ID定角度的情況相比，S為愈往下角度 愈大，入射光線在起始角度與大致固定角度相同的漸進式角度的結構 中可以有更多次的反射。圖3B是另一種漸變式的實施方式·垂直截面為 sin波或是類似Sin波的結構。這種結構有製造上與物性上的好處，而其 缺點是在它的波峰和波谷比較平坦’該部分切面的傾斜角度是小於45 度的’只有一次光伏轉換的機會。因此須把傾斜角度小於45度的部分， 其在水平面之投影佔整艎在水平面之投影的比例（如圖3B的網狀部分 佔整個起伏週期320的比例）縮小至50%以下，以減少轉換效率所受的 影響。另外，所謂的『隨著在該傾斜面上的位置不同而變化』也可以是 分段式傾斜。例如：傾斜面分為數段不同傾斜角度而各段傾斜角度大致 固定的分段線性式傾斜，或傾斜面分為數段不同漸變傾斜角度的分段 漸變式傾斜，或者是兩者的混合。 當本發明的非平面光吸收層往二維方向延伸就形成重複之錐體、倒立 錐體或兩者混合的側面，該錐體可以是水平截面為任何形狀的錐體’ 例如三角錐、四角錐…或是圓錐體。圖4A是以四角錐體為例的示意圖。 從通過錐體尖端的垂直截面4B來看，請參考圖4B，它的光吸收層 403、第一導電層402以及第二導電層404與光吸收層403相鄰的那一 201227978 面的垂直截面就與結構100的類似。其光線的反射或穿透特性也與前述 的結構100類似。圖5A是以倒立四角錐體為例的示意圖。圖5B係沿圖 5A之重複倒立四角錐體的錐體尖端之垂直截面示意圖。參考圖5b，它 的光吸收層503、第一導電層502以及第二導電層S04與光吸收層503 相鄰的那一面的垂直截面也是類似電池結構100。再者，其光線的反射 或穿透特性與前述的電池結構100的類似。圖6A係本發明以四角錐艎 與倒立四角錐體交錯的結構來實現之示意圖；圖63係在圖6A之交錯 的四角錐體與倒立四角錐體的垂直截面示意圖。如圖6B所示，它的光 吸收層603、第一導電層602以及第二導電層604與光吸收層603相鄰 的那一面的垂直截面也是類似電池結構1〇〇。再者，其光線的反射或穿 透特性與前述的電池結構100的類似。圖7A係本發明以四角錐體與倒 立四角錐體各取上半部所組合之結構來實現之示意圖；而圖7B係本 發明以四角錐體與倒立四角錐鱧各取下半部所組合之結構來實現之示 意圖》同樣地，其光線的反射或穿透特性與前述的電池結構1〇〇的類似。 此外，該重複之錐體、倒立錐體或兩者混合也可以是水平截面為不同 型狀所組合之錐體卡立錐體或兩者混合，例如水平截面的圖8中圓形 與斜線區域為不同形狀《如同前一段所提到的，錐體或倒立錐體的側 面也可以採用隨著在該面上的位置不同而變化的傾斜角度。以圓錐為 例，當採用前一段所提到的漸進式角度時，就形成了子彈形的結構。 也如同前_段所提_，姆於A賴定肖度的椎體，人射光線在起 始角度與大致13定角度相同的漸進式角度的結構_可以有更多次的反 201227978 射0 【圖式簡單說明】 圖1A係根據本發明之一種用於薄膜太陽能電池的結構之垂直截面示 意圖。 圖1B係以75度角傾斜為例’垂直入射光在本發明的太陽能電池中進 行數次反射的示意圖。為求簡單明瞭，在本圖中省略了光在行經各介 面時的折射角度。 圖2係當第二導電層為部分透明材質時，較大角度的入射光可在數處 光吸收層反應的示意圖。為求簡單明瞭，在本圖中省略了光在行經各 介面時的折射角度。 圖3A係漸進角度式非平面光吸收層示意圖。為求簡單明瞭，只顯示第 一導電層(斜線部分)與光吸收層相鄰那一側的垂直截面。 圖3B係波浪型(sin波或是類似sin波)非平面光吸收層示意圖。為求簡 單明瞭’只顯示第二導電層(斜線部分)與光吸收層相鄰那一側的垂直 截面。 圖4A係本發明以重複四角錐體的結構來實現的示意圖。 圖4B係在圖4A之重複四角錐體的垂直戴面示意圖。 圖5A係本發明以重複倒立四角錐體的結構來實現的示意圖。 12 201227978 圖5B係在圖5A之重複倒立四角錐體的垂直截面示意圖。 圖6A係本發明以四角錐體與倒立四角錐體交錯的結構來實現的示意 圖。 圖6B係在圖6A之交錯的四角錐想與倒立四角錐體的垂直截面示意圖。 圖7A係本發明以四角錐體與倒立四角錐體各取上半部所組合之結構 來實現的示意圖。 圖7B係本發明以四角錐體與倒立四角錐艎各取下半部所組合之結構 來實現的示意圖。 圖8係本發明以圓錐與另一種雖體混合時的水平截面示意圓。 【主要元件符號說明】 本發明 I 100薄膜太陽能電池結構 101保護層 102、 202、402、502'602 第一導電層 103、 203、403、503、603 光吸收層 104、 204、404、504、604 第二導電層 105基底 13201227978 VI. Description of the Invention: [Technical Field] The present invention relates to a thin film solar cell structure which allows multiple incident light to be reflected multiple times in a solar cell and causes multiple photovoltaic conversions, thereby generating more The electrical energy to improve the conversion efficiency of the solar cell. [Prior Art] A solar cell is a device that converts solar energy into electrical energy. If distinguished by material, it can be classified as bismuth, compound semiconductor, dye or organic solar cell. If the structure is distinguished, it can be roughly classified into a crystalline solar cell and a thin film solar cell. In the case of solar cells, S, usually monocrystalline and polycrystalline solar cells are crystalline solar cells, while amorphous germanium and microcrystalline solar cells are thin film solar cells. The light absorbing layer, the first conductive layer and the second conductive layer used in the conventional solar cell are planarly stacked, and the light reflected from the second conductive layer cannot be reused from the solar cell. Some known techniques propose ways to increase the probability of light staying in the light absorbing layer. For example, there are known techniques that use a coarse second conductive layer to change the angle of the reflected light so that some of the reflected light reaches the glass air interface and is totally reflected back to the solar cell, but not all of the light is totally reflected. There are also known techniques for making a undulation of a first conductive layer, a light absorbing layer, and a second conductive layer (referred to herein as a photo-volt conversion structure) to change the path of light travel in the photovoltaic conversion layer. While increasing the ratio of reflected light back to the light-to-volt conversion layer when the reflected light is in the glass-air interface, this also increases the reflection loss of light as it travels through the interface between the first conductive layer and the light absorbing layer. 201227978 And as mentioned above, these known techniques can only increase the probability of light staying in the light absorbing layer, and some of the light will leave the solar cell directly. SUMMARY OF THE INVENTION The present invention is a non-planar thin film photo-volt conversion structure having a vertical cross section like a sawtooth undulation, so that almost all of the normally incident light is reflected several times between non-planar structures, thereby causing several optical-volt conversions. And generate more power to improve conversion efficiency. The greatest difference from the known techniques mentioned in the preceding paragraph is that, first, the non-planar undulations of the present invention are more than three times larger than the thickness of the photo-volt conversion structure. In this way, almost all the remaining light of the incident light after a single photo-volt conversion is reflected by the second conductive layer to somewhere opposite the non-planar undulation and is again subjected to the optical-volt conversion, and continues to reflect until it leaves the non-planar undulation. region. In contrast, the texture of the aforementioned prior art has a scale smaller than the thickness of the photo-volt conversion structure, and the main purpose is to scatter the incident light and the light reflected by the second conductive layer into many different effects by scattering caused by small scale fluctuations. The direction of travel to increase the probability of light reflecting back within the light-volt conversion structure. However, in general, some of the light will leave directly or leave the light-volt conversion structure after only one or two reflections. Second, the non-planar undulation angle of the present invention is relatively large. Substantially all non-planar solar cells are subject to the problem of increased reflection losses as the light travels through the interface between the first conductive layer and the light absorbing layer. In order to have a more oblique angle, the so-called "reflection loss" in the present invention does not directly exit the solar cell as in the known technology, and is reflected to somewhere in the non-planar undulating plane and then converts the photovoltaic conversion if When the "reflection loss" appears again in "somewhere", the above action will continue until the last "reflection loss" of 201227978 leaves the non-planar undulating area. However, due to several reuses, the last remaining "reflection loss" should be minimized. [Embodiment] Referring to the vertical sectional view of Fig. 1A, the present invention relates to a thin film solar cell (e.g., a germanium semiconductor, a dye-sensitized solar cell, etc.), and the incident light can be in its non-planar light- A thin film solar cell structure 100 is provided with a plurality of reflections between the volt-conversion structures to increase conversion efficiency. The cell structure 100 includes at least one non-planar light absorbing layer 103, an at least partially transparent first conductive layer 1200, and an An optical-volt conversion structure in which at least partially transparent or completely reflective first conductive layer 104 is laminated, and a protective layer 101 and a substrate 105 which are selectively added. Wherein the first conductive layer 1〇2 forms a non-planar undulation with the light absorbing layer 103, and on the side away from the light absorbing layer 1〇3, the protective layer or the anti-reflection can be selectively added. In addition, the first conductive layer 102 can selectively electrically enhance the buffer layer between the interface with the light absorbing layer 〇3 to avoid conversion efficiency, such as the buffer layer used by CIS/CIGS. The protective layer 101 may use glass, transparent acrylic, transparent plastic or other transparent material, and on the side away from the first conductive layer 102, may form non-planar undulations together with the first conductive layer 1〇2. It is also possible to form a plane as shown in Fig. 1, and it is possible to selectively increase the anti-reflection treatment. The second conductive layer 104 may form a non-planar undulation with the light absorbing layer 103 on the side away from the light absorbing layer 1 , 3, or may form a plane as shown in FIG. 1; and when the battery The structure 1 is a process using a substrate structure (based on the second conductive 201227978 layer 104 or directly on the substrate 105, starting to deposit other layers of FIG. 1 upward), and may be in the second conductive layer 104. Selectively adding a substrate 105 of glass, stainless steel, acryl, plastic or other material on the side away from the light absorbing layer 103, if a process using a superstrate structure (using the protective layer 1〇1 as a substrate, starting the reverse Depositing the other layers of Figure 1 does not necessarily require the substrate 105. If necessary, an insulating film can be selectively added between the second conductive layer 104 and the substrate 105. The light absorbing layer 103 performs photo-volt conversion for a thin film solar cell, that is, a place where light is absorbed to generate electric energy. For example, if the structure of the present invention is applied to a conventional amorphous germanium thin film solar cell, the light absorbing layer 1 〇 3 is composed of a P-type amorphous germanium film, a type I amorphous germanium film and an N-type amorphous germanium film. Constructed. However, if the structure of the present invention is applied to a CIS/CIGS solar cell, the light absorbing layer 1〇3 is composed of a P-type CuInSeV Cu(In,Ga)Se2 and an N-type CuInSe〆Cu(In,Ga)Se2 film. Made. Since the above structure is a conventional technique, it will not be described again. In addition, according to a preferred embodiment of the present invention, referring to FIG. 1A, the height difference t between the peaks and valleys of the non-planar light absorbing layer 1〇3 is more than three times the thickness d, and the inclination angle is not less than 45 degrees ( 1B is 75 degrees) +, after the incident light is subjected to a light-volt conversion, almost all of the remaining light is reflected by the second conductive layer 104 to somewhere opposite the non-planar undulation and is again lighted. - Volt conversion 'and will continue to reflect until it leaves the non-planar undulating area. The first conductive layer 102 may be a single conductive material or may be formed of several conductive materials. In addition, the first conductive layer 102 can increase the electrode 201227978 (electrode finger and bus) formed of a material having a low resistance value (usually metal) according to requirements (for example, a large-area solar cell needs to reduce the series resistance of the surface electrode). Since the above application is a conventional technique, it will not be described again. The second conductive layer 104 may be a single conductive material or may be formed of several conductive materials. According to a preferred embodiment of the present invention, if the conversion efficiency is to be optimized, the second conductive layer 104 must be a fully reflective electrode. . The second conductive layer 1〇4 may be made of an at least partially transparent material depending on the particular needs of the application, such as solar cells that require light transmission in the building. That is, the present invention can select the second conductive layer 104' having different reflectances as needed, and the reflectance can range from 20% to 100%. Since several reflections between non-planar light-volt conversion structures are the main factors for increasing conversion efficiency, the second conductive layer 104 is not recommended to use a material having a reflectance of less than 20%, and a reflectance of 40% or more is preferable. It is best to be above 60%. When the second conductive layer 1〇4 is a fully reflective electrode, the remaining incident light can be reflected to the other side of the thin film solar cell, and photovoltaic conversion can be performed again to generate electric energy. The number of times a normal incident light can produce a photo-volt transition is related to the angle (inclination angle) between the plane of the contact point of the incident light on the second conductive layer 104 and the plane. When the inclination angle of each inclined surface of the second conductive layer 104 adjacent to the light absorbing layer 1〇3 is greater than 45 degrees, 'every vertical incident light can cause several times of light-volt conversion to generate more electric energy. , improve conversion efficiency. For example, when the tilt angle is 75 degrees, referring to FIG. m, the second conductive layer 104 can reflect the normal incident light 1〇6 six times, that is, react with the light absorbing layer 103 six times to generate electric energy. opportunity. When the tilt angle is 6 degrees, each vertical light of 201227978 can cause three reflections, that is, three times of reaction with the light absorbing layer and generate electric energy. Similarly, when the tilt angle is 45 degrees, each vertical Incident light can cause secondary reflections', that is, there is a second chance to react with the light absorbing layer and generate electrical energy. If the tilt angle is less than 45 degrees, then even some of the normally incident light has only one light absorbing layer to react and generate electrical energy. Therefore, the 'inclination angle less than 45 degrees is not recommended (since the process caused a small proportion of peaks and troughs inclined less than 45 degrees is acceptable); 50 degrees (inclusive) or more is recommended; preferably at 60 degrees (inclusive) or above. Further, as shown in Fig. 1B, the two opposite inclined faces have the same inclination angle (75 degrees); however, the two opposite inclined faces may also adopt different angles. Two adjacent troughs can be on different horizontal planes; two adjacent peaks can also be at different heights. Sometimes, depending on the requirements of use, such as when used on a building, the solar cell is required to be partially transparent, and the second conductive layer 204 must be at least partially transparent. At this time, the incident light irradiated on the second conductive layer 204 has transmitted light in addition to the reflected light. The intensity of the reflected light is weakened compared to the condition of using the fully reflective second conductive layer. Because there is transmitted light, please refer to the circle mark in Figure 2. This structure is for obliquely incident light (for example, 206, 207). However, it is possible to provide several opportunities for generating electric energy by reacting with the light absorbing layer 2〇3. When several layers of light absorbing layers are used, it is possible to choose from a plurality of layers of spectral absorption covering a range of light absorbing layers to increase the use of the incident spectrum. An electrically conductive buffer layer may be selected between the respective light absorbing layers. 201227978 In addition, the inclination angle of the surface of the first conductive layer and the light absorbing layer (that is, the inclination angle of the non-planar light absorbing layer 103) may also be changed according to the position on the inclined surface, such as a gradient. Style. FIG. 3A is an embodiment of a gradation structure. In the present invention, the progressive angle is larger as the angle is lower, and the incident ray is at a starting angle and a substantially fixed angle. There can be more reflections in the same progressive angle structure. Fig. 3B is another gradual embodiment. The vertical cross section is a sin wave or a structure similar to a Sin wave. This structure has manufacturing and physical benefits, but has the disadvantage that its peaks and troughs are relatively flat. The slope of the section is less than 45 degrees and there is only one chance of photovoltaic conversion. Therefore, the portion of the inclined angle less than 45 degrees, the projection of the horizontal plane in the horizontal plane should be reduced to 50% or less in proportion to the projection of the entire horizontal plane (as shown in Fig. 3B). The impact of efficiency. Further, the so-called "changes depending on the position on the inclined surface" may be a segmented tilt. For example, the inclined surface is divided into several segments of different inclination angles, and the segmentation linear inclination of each segment is substantially fixed, or the inclined surface is divided into several segments of different gradient inclination angles, a stepwise gradient, or a mixture of the two. When the non-planar light absorbing layer of the present invention extends in a two-dimensional direction to form a repeating cone, an inverted cone or a side of a mixture of the two, the cone may be a cone of any shape in a horizontal section, such as a triangular cone, four The pyramid is... or a cone. Fig. 4A is a schematic view showing a quadrangular pyramid as an example. Referring to the vertical section 4B passing through the tip end of the cone, please refer to FIG. 4B, the vertical cross section of the 201227978 plane of the light absorbing layer 403, the first conductive layer 402, and the second conductive layer 404 adjacent to the light absorbing layer 403. It is similar to structure 100. The reflection or transmission characteristics of the light are also similar to the structure 100 described above. Fig. 5A is a schematic view showing an inverted quadrangular pyramid as an example. Figure 5B is a vertical cross-sectional view of the tip of the cone of the inverted quadrangular pyramid repeated along Figure 5A. Referring to Fig. 5b, the vertical cross section of the light absorbing layer 503, the first conductive layer 502, and the side of the second conductive layer S04 adjacent to the light absorbing layer 503 is also similar to the battery structure 100. Moreover, the reflection or transmission characteristics of the light are similar to those of the battery structure 100 described above. Fig. 6A is a schematic view showing the structure in which the quadrangular pyramid and the inverted quadrangular pyramid are staggered; Fig. 63 is a schematic vertical sectional view of the interleaved quadrangular pyramid and the inverted quadrangular pyramid of Fig. 6A. As shown in Fig. 6B, the vertical cross section of the side of the light absorbing layer 603, the first conductive layer 602, and the second conductive layer 604 adjacent to the light absorbing layer 603 is also similar to the battery structure. Moreover, the reflection or penetration characteristics of the light are similar to those of the battery structure 100 described above. 7A is a schematic view of the present invention in which the quadrangular pyramid and the inverted quadrangular pyramid are combined with the upper half; and FIG. 7B is a combination of the quadrangular pyramid and the inverted quadrangular pyramid. The structure is realized by the same structure. Similarly, the reflection or transmission characteristics of the light are similar to those of the aforementioned battery structure. In addition, the repeating cone, the inverted cone or a mixture of the two may also be a cone-shaped pyramid having a combination of different shapes in a horizontal section or a mixture of the two, for example, the circular and oblique areas in FIG. 8 of the horizontal section are Different Shapes As mentioned in the previous paragraph, the sides of the cone or inverted cone can also adopt an angle of inclination that varies with the position on the face. Taking a cone as an example, when the progressive angle mentioned in the previous paragraph is used, a bullet-shaped structure is formed. Also as mentioned in the previous paragraph, _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1A is a schematic vertical cross-sectional view showing a structure for a thin film solar cell according to the present invention. Fig. 1B is a schematic diagram in which the vertical incident light is reflected several times in the solar cell of the present invention as an example of tilting at an angle of 75 degrees. For the sake of simplicity, the angle of refraction of light as it travels through the various interfaces is omitted in this figure. Fig. 2 is a schematic view showing a reaction of a large angle of incident light at a plurality of light absorbing layers when the second conductive layer is a partially transparent material. For the sake of simplicity, the angle of refraction of light as it travels through the interfaces is omitted in this figure. Figure 3A is a schematic illustration of a progressive angle non-planar light absorbing layer. For the sake of simplicity, only the vertical section of the side of the first conductive layer (hatched portion) adjacent to the light absorbing layer is shown. Figure 3B is a schematic diagram of a non-planar light absorbing layer of a wave type (sin wave or similar sin wave). For the sake of simplicity, only the vertical section of the side of the second conductive layer (hatched portion) adjacent to the light absorbing layer is shown. 4A is a schematic view of the present invention implemented by repeating the structure of a quadrangular pyramid. Figure 4B is a schematic illustration of the vertical wear of the repeating quadrangular pyramid of Figure 4A. Fig. 5A is a schematic view of the present invention realized by repeating the structure of an inverted quadrangular pyramid. 12 201227978 Figure 5B is a vertical cross-sectional view of the inverted inverted quadrangular pyramid of Figure 5A. Fig. 6A is a schematic view showing the structure of the present invention in which a quadrangular pyramid and an inverted quadrangular pyramid are staggered. Figure 6B is a schematic vertical cross-sectional view of the staggered quadrangular pyramid and the inverted quadrangular pyramid of Figure 6A. Fig. 7A is a schematic view showing the structure of the present invention in which the quadrangular pyramid and the inverted quadrangular pyramid are each combined with the upper half. Fig. 7B is a schematic view showing the structure of the present invention in which the quadrangular pyramid and the inverted quadrangular pyramid are each combined with the lower half. Fig. 8 is a schematic cross-sectional view of the horizontal cross section of the present invention when the cone is mixed with another body. [Main component symbol description] The present invention I 100 thin film solar cell structure 101 protective layer 102, 202, 402, 502'602 first conductive layer 103, 203, 403, 503, 603 light absorbing layer 104, 204, 404, 504, 604 second conductive layer 105 substrate 13