201019491 九、發明說明 【發明所屬之技術領域】 本發明關於電化學沈積金屬的方法，特別關於一種在 太陽能電池的陰極表面電化學沈積金屬電極的方法。 【先前技術】 目前絕大多數商業化太陽能電池的導電電極生成方法 0 是，用絲網印刷的方法，在太陽能電池的陰極表面刷上銀 漿、在陽極表面刷上鋁漿，再經過高溫共燒後，在該太陽 能電池的陰極和陽極上同時生成導電陰極和陽極。這種太 陽能電池導電電極生成方法的優點是方法簡單可靠，容易 在大規模生產上得到應用。 但是，絲網印刷和共燒生成太陽能電池導電電極的簡 單方法限制了太陽能電池的光電轉換效率的提高。爲了確 保絲網印刷的漿料在共燒後能與太陽能電池的表面有較好 ❹ 的歐姆接觸，降低太陽能電池的串聯電阻，不僅必須採用 較粗的金屬副柵線的設計（一般大於100微米），而且還 必須採用較低的發射極方塊電阻的設計（一般在50歐姆 每平方）。較粗的金屬副柵線的設計降低了太陽能電池的 有效工作面積，而較低的發射極方塊電阻的設計降低了太 陽能電池的短路電流，這是目前商業化太陽能電池的光電 轉換效率偏低的主要原因。 很明顯，提高太陽能電池的光電轉換效率的主要措施 之一是提高其發射極的方塊電阻。但是，太陽能電池發射 -5- 201019491 極的方塊電阻提高後，如果繼續採用絲網印刷漿料和共燒 的方法，將會增加太陽能電池的接觸電阻，從而降低太陽 能電池的光電轉換效率。因此，提高太陽能電池發射極的 方塊電阻後必須解決的問題之一是降低金屬導電電極和太 陽能電池之間的接觸電阻。 解決上述問題的方法之一是採用選擇性擴散方法。所 謂的選擇性擴散方法是指在太陽能電池的發射極的不同區 域生成兩種不同値的方塊電阻，即，在生成金屬導電電極 _ 的區域具有較低的方塊電阻，在其他受光表面具有較高的 方塊電阻。這種方法設計既能提高太陽能電池的短路電 流，又能降低金屬導線和太陽能電池之間的接觸電阻。因 此，選擇性擴散方法是提高太陽能電池的光電轉換效率的 主要措施之一。 但是，上述絲網印刷和共燒方法很難應用在使用了選 擇性擴散方法的太陽能電池上。其主要原因是絲網印刷方 法很難把金屬漿料對準在太陽能電池發射極具有較低方塊 @ 電阻的區域上。 解決該對準問題的常用方法是在太陽能電池表面採用 化學沈積生成金屬導電電極的方法來替換以上所述的絲網 印刷的方法。埋柵太陽能電池就是採用化學沈積金屬銅的 方法在太陽能電池的發射極上生成金屬導電電極的。其具 體方法是，用鈍化膜或減反膜覆蓋具有較大方塊電阻的發 射極表面，採用雷射在鈍化膜上開槽後，再進行深擴散， 從而降低該發射極表面開槽區域的方塊電阻，最後採用化 -6 - 201019491 學沈積金屬的方法，在具有較低方塊電阻的發射極區域生 成太陽能電池的金屬導電電極。 化學沈積銅的過程是一個相當緩慢的化學過程，一般 需要近10小時左右的時間才能達到所需的金屬導電電極 的厚度。爲了防止由於沈積速度太快而引起的應力和吸附 問題，一般把化學沈積金屬導電電極的速率控制在每小時 2微米以下。 Φ 用化學沈積金屬的方法製備太陽能電池電極的方法還 存在另外一個問題，即化學沈積金屬溶液的使用壽命比較 短，一般只能使用幾個批次就不能繼續使用。因此化學沈 積金屬的方法在大規模生產上使用時會產生大量的廢水。 由於排放的廢水中含有一些比較難以處理的有機物，因此 使用化學沈積金屬的方法增加了太陽能電池的生產成本。 不僅如此，化學沈積金屬的溶液相當不穩定，很容易 發生自析金屬的現象，影響正常的生產。另外，化學沈積 φ 金屬的方法條件的控制也非常的苛刻。例如，化學沈積銅 溶液的溫度控制要求嚴格。爲了減小自析銅的可能性，在 化學沈積銅的時候，不僅要求空氣鼓泡，還要求過濾。爲 了保持溶液濃度的穩定，還要求不斷地添加補充液。補充 液的添加必須非常嚴格地控制，太多了會造成自析銅，太 少了會減小沈積銅的速率。 另外，絕大多數的化學沈積銅的操作是在高於室溫下 進行的，例如大於5(TC，這樣的方法就需要大量的能源 提供，進一步加大了生產成本。由於反應時間較長，這些 201019491 能源的消耗量在生產過程中是相當可觀的。 解決以上問題的方法之一是採用電鍍方法取代化學& 積金屬的方法。相對於化學沈積金屬，電鍍方法的優點胃 沈積金屬的速度快。採用電鍍方法後，可以把太陽能電& 的導電電極的生成時間從化學沈積金屬的近10小時的@ 程縮短到1小時之內。在一般情況下，採用電鍍方法後， 製備太陽能電池的導電電極的過程可在十幾分鐘內完成。 採用電鍍方法取代化學沈積金屬的方法的另一個優，點 是，由於電化學沈積金屬比化學沈積金屬的過程簡單得^ 多，因此操作範圍要大得多，特別適用於工業生產。例 如，它對溫度的要求不高，一般可在室溫下操作，這樣既 有利於生產控制，又節約了加熱所需要的成本。電鍍所用 的電解液的組成也非常簡單，所以在一般情況下電解液可 以長時間反復地使用。 更進一步，一般的化學沈積過程所生成的太陽能電池 的導電電極是非晶狀態的，而電化學沈積的太陽能電池的 金屬導電電極是呈微晶狀態的，因此電化學沈積的金屬導 電電極具有更好的導電性能。它的直接影響是電鍍金屬電 極能降低太陽能電池所產生的電流在金屬導電電極上的損 失，從而提高太陽能電池的轉換效率。 由於電鍍方法沈積金屬的化學非常簡單，例如，電解 液的pH値和溶液組成的變化對電鍍方法的影響不大，對 溶液的管理也非常簡單，因此電鍰方法非常適用於工業化 生產。更重要的是，採用電鍍方法生成的太陽能電池的金 -8- 201019491 屬導電電極的生產成本非常低，對廢液的處理工序也要比 化學沈積金屬的廢液處理簡單得多。 但是，要把傳統的電鍍方法真正應用於大規模生產太 陽能電池，還有一定的困難。主要問題是電鍍掛具和太陽 能電池的接觸，以及在太陽能電池上所鍍的金屬的均勻 性。上述電鍍掛具是傳統電鍍操作過程中的一個重要工 具，其在電鍍操作過程中的作用之一是把被電鍍的物體固 Φ 定在一定的位置，或固定在一定的範圍；電鍍掛具的另一 個作用是把外置電源的電流傳導給被電鍍的物體。 事實上，在金靥化之前，太陽能電池的表面的電阻非 常大，在通常情況下，電鍍掛具和太陽能電池表面的接觸 電阻很大，最終造成鍍在太陽能電池表面的金屬的均勻性 很差。另外，由於製備太陽能電池的半導體材料非常脆， 因此，在將太陽能電池裝卸於電鍍掛具的過程中，經常會 發生太陽能電池的碎裂。 • 通常解決上述由於太陽能電池與電鍍掛具之間的機械 接觸和電接觸所造成的問題的方法是，將太陽能電池浸沒 在電解質內，利用太陽能電池在光照下所產生的電能，在 太陽能電池上沈積金屬導電電極。由於依靠光照後太陽能 電池所產生的電能在太陽能電池的表面生成金屬導電電 極，因此該方法不需要依靠傳統的電鏟掛具將外置電源的 電流傳導給太陽能電池的需要被電鍍的表面，解決了由於 使用電鍍掛具所造成的各種問題。 但是，這種利用太陽能電池自身產生電能的方法來實 -9- 201019491 現在太陽能電池表面沈積金屬的方法也有很多缺陷。首 先，爲了保護太陽能電池陽極表面上的金屬，必須外加一 個直流電源。該直流電源的陽極接到位於電解質溶液內的 金屬上，該直流電源的陰極接到位於電解質溶液內的太陽 能電池的陽極金屬上。這樣的連接才能保證當在太陽能電 池的陰極上沈積金屬時該太陽能電池的陽極上的金屬不會 被破壞。事實上，在沈積金屬時使用這樣的連接方式會使 得太陽能電池的陰極和陽極同時在沈積金屬，造成了生產 成本的不必要的增加。 這種方法的另外一個缺點是，由於太陽能電池的陰極 表面所存在的電勢，是太陽能電池所產生的電勢和外置電 源的電勢的總和，太陽能電池陰極表面上的電勢不僅取決 於太陽能電池所產生的電勢，還取決於外置電源所施加在 太陽能電池上的電勢。因此，太陽能電池表面上所鍍金屬 的均勻性不僅取決於光照在太陽能電池表面上的均勻性， 而且還取決於外置電源施加在太陽能電池上的電勢的均勻 性。例如，只有非常良好的整個表面的接觸才能夠在太陽 能電池陰極表面得到非常均勻的電勢。事實上，這種均勻 的接觸是很難在工業生產中實現的。 【發明內容】 針對以上現有技術中的各項缺陷，本發明的目的之一 是提供一種利用太陽能電池在接受光照後產生電勢的特 點，在太陽能電池的陰極表面上實現電化學沈積金屬的方 -10- 201019491 法。 進一步，本發明的另一個目的，是提供一種能確保金 屬只沈積在太陽能電池的陰極表面的電化學沈積金屬的方 法。 更進一步，本發明的另一個目的，是提供一種能夠有 效控制金屬沈積速率的在太陽能電池的陰極表面電化學沈 積金屬的方法。 Φ 本發明的最後一個目的，是提供一種適用於大規模生 產的在太陽能電池的陰極表面沈積金屬的方法。 爲了實現上述目的，本發明提出了一種電化學沈積太 陽能電池金屬電極的方法，其包括以下步驟： 將太陽能電池的含有陰極的表面與電解質溶液接觸； 將太陽能電池的陽極和固體金屬連接； 使用光源對太陽能電池的主受光表面進行光照； 該電解質溶液中的金屬離子接受該太陽能電池陰極表 面產生的電子後生成金屬並沈積在該太陽能電池的陰極表 面，同時該固體金屬爲該太陽能電池的陽極提供電子後生 成金屬離子並溶入電解質溶液。 該太陽能電池除了含有陰極的表面外不與該電解質溶 液接觸。 該太陽能電池與該電解質溶液接觸的表面只含有陰 極〇 該太陽能電池與該電解質溶液接觸的表面可以同時含 有陰極和陽極 -11 - 201019491 該電解質溶液包括金屬離子、酸根、水和添加劑。 該電解質溶液含有至少一種或一種以上的金屬離子。 該電解質溶液含有至少一種或一種以上的酸根。 該電解質溶液還包括一種或一種以上的添加劑。 該主受光表面爲該太陽能電池與該電解質溶液相接觸 的表面或者其未與該電解質溶液接觸的表面。 在該進行光照的步驟中，光照的光源爲自然光或照明 器件發出的光。 在該進行光照的步驟中，光直接照射到太陽能電池的 表面或者透過電解質或其他介質後照射到太陽能電池的表 面。 該太陽能電池的陽極和該固體金屬通過導線電連接。 該固體金屬由至少一種金屬或合金組成。 該固體金屬至少有一個表面接觸該電解質溶液。 該方法還包括在太陽能電池的陽極和固體金屬之間連 接外置電源的步驟。 @ 該外置電源爲直流電源’其中該直流電源的陰極連接 該太陽能電池的陽極，該直流電源的陽極連接該固體金 屬。 該直流電源的輸出功率不小於零。 該固體金屬的成分與沈積在太陽能電池陰極表面上的 金屬成分相同。 該太陽能電池固定在電解質溶液的上方。 該太陽能電池在水平方向移動。 -12- 201019491 在本發明的電化學沈積金屬的過程中，金屬離子只能 沈積在太陽能電池的陰極上，從而從根本上解決了由於金 屬沈積在陽極造成短路而引起的電池效率下降的問題，同 時避免了使用任何電接觸損壞太陽能電池片以及造成沈積 金屬不均勻的可能。 本發明的另一個優點是，太陽能電池的另一表面不和 電解質溶液接觸，因此不需要加一個外置電源以保護太陽 Φ 能電池的另一表面的金屬。從而太陽能電池表面的電勢可 以從零開始變化，並能進行有效的控制，從而控制太陽能 電池陰極表面的電化學反應速率。 本發明的另一個重要優點是，由於保證了光照強度的 均勻，太陽能電池的電勢在整個表面是非常均勻的，從而 在整個太陽能電池的陰極表面所沈積的金屬也是非常均勻 的。 本發明的再一個優點是能夠達到自我對準的效果。該 優點特別有利於製備具有選擇性擴散結構的太陽能電池。 【實施方式】 下面參照圖式對本發明的具體實施例進行詳細說明。 圖1爲使用本發明的電化學沈積金屬的方法在太陽能 電池的陰極表面進行電化學反應以沈積金屬的示意圖。 如圖所示，本發明的電化學沈積金屬的方法使用的裝 置主要是電解質溶液槽10，電解質溶液20，太陽能電池 30，金屬導線40，金屬塊50和發光器件60。 -13- 201019491 本發明的電解質溶液槽ίο的主要作用是盛放電解質 溶液20。在太陽能電池30的主受光表面是其陰極表面的 情況下’本發明的電解槽10的另一個作用是允許發光器 件60所發出的光能透射到太陽能電池3 0的主受光表面。 這樣’本發明的電解質槽10 —般可採用透明耐腐蝕的材 料製成，如石英，玻璃，透明有機材料等。 當太陽能電池的主受光面不含其陰極的情況下，即， 其主受光面與陰極表面分別爲太陽能電池的兩面時，發光 器件應該放置在太陽能電池的上方，使其所發出的光直接 照射在太陽能電池的上表面。 本發明的電解質溶液槽10內的電解質溶液20主要是 由金屬離子和酸根所組成，例如硫酸銅，氯化鎳等。根據 所沈積金屬的不同要求，電解質溶液20可以僅含有一種 金屬離子，也可以含有多種金屬離子。 同樣，根據不同的沈積金屬的要求，電解質溶液20 內可以僅含有一種酸根，也可以含有多種酸根，如硫酸根 和硝酸根。 爲了減少沈積金屬的應力和提高所沈積的金靥的平整 度，根據不同的電解質溶液和電化學沈積金屬的方法，也 可以在電解質溶液20內加入適當的添加劑。 本發明的一個重要技術特徵是，太陽能電池30只有 其含有陰極的一個表面與電解質溶液20相接觸，而另一 表面並不和電解質溶液20接觸。 爲了工業生產的簡單性，90%以上的商業化太陽能電 201019491 池的兩個表面分別爲陰極和陽極。因此本發明的方法特別 適用於在這種商業化太陽能電池上沈積金屬。當本發明的 方法用於上述商業化太陽能電池時，由於其陽極在其陰極 的反面並且不和電解質溶液接觸，因此不一定需要連接外 置電源以保護太陽能電池陽極上的金屬。 如圖1所示，固體金屬50和太陽能電池30之間用導 電線40電連接。在一般情況下，固體金屬50的主要成分 φ 與要沈積在太陽能電池30陰極表面上的金屬成分相同。 固體金屬50可以是單一成分的金屬，也可以是由一 種以上的金屬所組成的合金。該固體金屬50可以被放置 到電解槽10內的任何一個位置，同時和電解質溶液20有 良好的接觸。當太陽能電池30的陰極是主受光面時，固 體金屬50所放置的位置不應影響到發光器件60所發出的 光投射到太陽能電池3 0的表面。 圖1展示了使用本發明的方法在太陽能電池的陰極表 面電化學沈積金屬電極的完整的反應過程。 和傳統的電鍍方法不同，本發明的電化學反應可以不 需要外界提供電能，而是利用太陽能電池自身產生的電能 來實現電化學反應。 在圖1中，發光器件60位於電解槽10的下方。該發 光器件60所處的位置取決於太陽能電池30的結構。在太 陽能電池30的陰極是該太陽能電池的主受光面的情況 下，該發光器件60所發出的光，透過透明的電解槽10後 .再透過電解質溶液20，照射到太陽能電池30的下表面即 -15- 201019491 陰極表面。 太陽能電池是一種將光能轉換爲電能的器件。當太陽 能電池受到光的照射後，在發射極，即陰極，的表面產生 負電勢。因此上述光照使太陽能電池30產生負電勢後釋 放電子。電解質溶液20中的金屬離子在負電勢的驅動下 向陰極移動，在太陽能電池30的陰極表面接受電子後， 生成金屬原子並沈積在太陽能電池30的陰極表面。同 時，在電解質溶液20內的固體金屬50，通過導電線40, 在太陽能電池30的陽極正電勢的作用下，不斷地失去電 子生成金屬離子後溶解入電解質溶液20中，以保持電解 質溶液20中的金屬離子濃度的穩定。最終實現無需外部 電源供電的電化學反應過程。 和需要連接外置電源的電鍍過程不同，本發明的上述 電化學沈積金屬的過程不需要連接外置電源，而是靠光照 後太陽能電池30自身所產生的電勢來實現整個電化學反 應，因此上述過程中金屬離子只能沈積在太陽能電池30 的陰極上。 這個特徵在工業生產太陽能電池中有著非常重要的意 義。如果連接外置電源實現電化學反應，太陽能電池表面 上沒有被保護的陰極和陽極都會沈積上金屬，造成太陽能 電池的短路，降低太陽能電池的光電轉換效率。而本發明 的方法中，即使存在暴露的陽極表面，但由於在太陽能電 池接收到光照後，在其陽極只能接受電子而不能釋放電 子，所以金屬不可能沈積在太陽能電池的陽極上，從而從 -16- 201019491 根本上解決了由於陽極短路所造成的電池效率下降的問 題。 同時，由於太陽能電池片的厚度—般在200微米左 右，任何局部的物理接觸都很容易造成碎裂’而本發明的 電化學沈積金屬過程可以不需要連接外置電源’因此本發 明的電化學過程可以不使用任何電接觸’從而避免了損壞 太陽能電池片的可能。 A 更進一步，由於太陽能電池的陰極表面的電阻一般比 w 較大，如果依靠外部電接觸就會造成在太陽能電池的陰極 表面的電勢不均勻，最終導致在太陽能電池的表面沈積的 金屬不均勻。而在本發明的電化學反應中’只要光照強度 在太陽能電池的表面是均勻的，太陽能電池所產生的電勢 在其整個表面也是均勻的，即，在其表面沈積的金屬是均 勻的。 另一方面，在本發明的電化學反應過程中，含有太陽 φ 能電池陰極的表面和電解質溶液接觸，太陽能電池的另一 表面不和電解質溶液接觸，因此不必使用外置電源保護太 陽能電池的另一表面的金屬。這樣，太陽能電池表面的電 勢可以從零開始變化，能很好地控制在太陽能電池陰極表 面的電化學反應速率，電化學沈積金屬的速率也可以通過 改變光照強度進行任意的變化。 本發明的方法製成的太陽能電池的陰極表面所沈積的 金屬是非常均勻的。這是因爲太陽能電池產生的電勢正比 於它所接收到的光照強度，只要在保證光照強度均勻的條 -17- 201019491 件下，太陽能電池的電勢在整個表面是非常均勻的，不受 陽極金屬塊所處的位置、形狀和尺寸的影響。均勻的電勢 產生了均勻的電化學反應速率，因此也就能得到均勻的金 屬沈積層。 本發明的方法特別有利於製備具有選擇性擴散結構的 太陽能電池。爲了減少太陽能電池的反射率，在其具有高 方塊電阻的表面上一般會鍍上一層降低反射率的減反膜。 這層減反膜在本發明電化學沈積金屬的過程中作爲掩膜， 阻止太陽能電池的陰極所產生的電子與電解質溶液中的金 屬離子接觸。而在進行過選擇性擴散的低方塊電阻表面沒 有該掩膜的保護，太陽能電池所產生的電子和電解質溶液 內的金屬離子接觸，發生電化學反應，在其表面生成金屬 導電電極。 本發明的電化學沈積金屬的過程可以是間隙的，也可 以是連續的。 在間隙電化學沈積金屬的過程中，本發明的太陽能電 池30被固定在電解質溶液20的上方，其含有陰極的表面 與電解質溶液20接觸。當太陽能電池30接收到發光器件 60所發出的光後，電解質溶液20中的金屬離子就會在太 陽能電池的陰極表面接收到電子，生成金屬並沈積在太陽 能電池的陰極表面。 在連續電化學沈積金屬的過程中，本發明的太陽能電 池30在水平方向移動。移動太陽能電池30的方式可以是 滾輪，或者是移動支架。例如，太陽能電池30可以被放 201019491 置在一組滾輪上，其含有陰極的表面和在其下面的電解質 溶液20接觸，當這組滾輪向某一方向轉動時，太陽能電 池30就在這組滾輪上沿著該方向移動，實現連續電化學 沈積金屬的過程。 以下爲使用本發明的方法的幾個具體實施例。 一、第一實施例 第一步爲製作傳統太陽能電池： φ P型矽片在經過制絨，擴散，邊緣刻蝕，N型表面氮 化矽鑛膜，P型表面絲網印刷鋁漿，N型表面絲網印刷銀 漿，經燒結後測得該太陽能電池的光電轉換效率爲 16.5 7%，其中它的開路電壓，電流密度，串聯電阻，並聯 電阻和塡充因數分別爲 625mV; 35.3mA/cm2; 0.0075Ω; 1 3 · 1 1 Ω ; 7 5 . 1 %。 第二步爲配製電解質溶液： 銅電解質溶液的配製：把200克硫酸銅，120克硫 ❿ 酸，4.5毫升光亮劑VF100，均勻地溶入1升的水中。 錫電解質溶液的配製：將50克硫酸亞錫，60克硫 酸，48克酚磺酸，2.4克甲酚均勻地溶入1升的水中。 第三步爲電化學沈積金屬： 把太陽能電池的陰極表面和上述銅電解質溶液接觸， 太陽能電池的陽極和在銅電解質溶液內的固體銅連接。發 光器件放置在透明的電解質溶液槽的下部。在太陽能電池 受到光照15分鐘後，測得沈積在太陽能電池的陰極導電 電極上的銅層厚度約爲10微米。 -19- 201019491 然後再把經上述步驟得到的太陽能電池的陰極和上述 錫電解質溶液接觸，太陽能電池的陽極和在錫電解質溶液 內的固體錫連接。發光器件放置在透明的電解質溶液槽的 下部。在太陽能電池受到光照1分鐘後，測得沈積在太陽 能電池的陰極導電電極上的錫層厚度約爲0.01微米。同 時測得該太陽能電池的光電轉換效率被提高到16.94%， 其中它的開路電壓爲626mV，電流密度爲35.2mA/cm2， 串聯電阻爲0.0045Ω，並聯電阻爲49.41Ω，塡充因數爲 A 7 6.9%。 二、第二實施例 第一步爲製作埋柵電池： P型矽片在經過制絨，淺擴散，邊緣刻蝕，氧化，在 N型表面用雷射刻埋柵槽，在埋柵槽內深擴散，在P型表 面濺射鋁，然後鋁燒結，在埋柵槽內進行化學鍍鎳，再進 行鎳燒結後形成鎳矽合金。 第二步爲配製電解質溶液： @ 錬電解質溶液的配製：將150克硫酸鎳，8克氯化 鈉，30克硼酸，40克無水硫酸鈉，均勻地溶入1升的水 中〇 銅電解質溶液的配製：把200克硫酸銅，120克硫 酸，4.5毫升光亮劑VF100，均勻地溶入1升的水中。 銅鋅合金電解質溶液的配製：把75克氰化亞銅，9 克氰化鋅，55克氰化鈉，10克碳酸鈉，4克氟化鈉，均 勻地溶入1升的水中。 -20- 201019491 第三步爲電化學沈積埋柵電池陰極金屬： 把該太陽能電池的陰極表面和上述鎳電解質溶液接 觸，太陽能電池的陽極和在鎳電解質溶液內的固體鎳連 接。發光器件放置在透明的電解質溶液槽的下部。在太陽 能電池受到光照5分鐘後，測得沈積在太陽能電池的埋柵 槽內的鎳層厚度約爲0.1微米。 再把經過上述步驟的太陽能電池的陰極表面和上述銅 φ 電解質溶液接觸，該太陽能電池的陽極和在銅電解質溶液 內的固體銅連接。發光器件放置在透明的電解質溶液槽的 下部。在太陽能電池受到光照20分鐘後，測得沈積在太 陽能電池的埋柵槽內的銅層厚度約爲15微米》 然後再把經過上述步驟的太陽能電池的陰極表面和上 述銅鋅合金電解質溶液接觸，該太陽能電池的陽極和在銅 鋅合金電解質溶液內的固體銅鋅合金連接。發光器件放置 在透明的電解質溶液槽的下部。在太陽能電池受到光照2 φ 分鐘後，測得沈積在太陽能電池的埋柵槽內的銅鋅合金層 厚度約爲0·01微米。同時測得該太陽能電池的光電轉換 效率爲17.53%，其中它的開路電壓爲620mV，電流密度 爲 35.7mA/cm2，串聯電阻爲 0.0040Ω，並聯電阻爲 >100Ω，塡充因數爲79.2%。 三、第三實施例 第一步爲製作全背面導電電極太陽能電池： 在Ν型矽片上制絨，Ν型擴散，氧化，採用光刻膠作 爲掩膜把Ρ型電極接觸區打開，Ρ型深擴，採用光刻膠作 -21 - 201019491 爲掩膜把N型電極接觸區打開，在電極接觸區進行化學 鍍鎳，再進行鎳燒結後形成鎳矽合金。 第二步爲配製電解質溶液： 鎳電解質溶液的配製：將150克硫酸鎳，8克氯化 鈉，30克硼酸，40克無水硫酸鈉，均勻地溶入1升的水 中。 銅電解質溶液的配製：把200克硫酸銅，120克硫 酸，4.5毫升光亮劑VF100，均勻地溶入1升的水中。 銅錫電解質溶液：把20克氰化亞銅，30克錫酸鈉， 20克氰化鈉，10克氫氧化鈉，均勻地溶入1升的水中。 第三步爲電化學沈積全背面導電電極太陽能電池電 極： 把該太陽能電池的導電電極表面和上述鎳電解質溶液 接觸，該太陽能電池的陽極和一個外置電源的陰極相聯 接，該外置電源的陽極和在鎳電解質溶液內的固體鎳連 接。發光器件放置在太陽能電池的上部。把外置電源的輸 出電流控制在1安培，在太陽能電池受到光照5分鐘後， 測得沈積在太陽能電池的陰極表面的鎳層厚度約爲〇. 1微 米，測得沈積在太陽能電池的陽極表面的鎳層厚度約爲 0.08微米。 再把經過上述步驟的該太陽能電池的導電電極表面和 上述銅電解質溶液接觸，太陽能電池的陽極和一個外置電 源的陰極相聯接，該外置電源的陽極和在銅電解質溶液內 的固體銅連接。發光器件放置在太陽能電池的上部。把外 -22- 201019491 置電源的輸出電流控制在1 . 5安培，在太陽能電池受到光 照20分鐘後，測得沈積在太陽能電池的陰極表面的銅層 厚度約爲15微米，測得沈積在太陽能電池的陽極表面的 銅層厚度約爲12微米。 然後再把經過上述步驟的該太陽能電池的導電電極表 面和上述銅錫電解質溶液接觸，該太陽能電池的陽極和一 個外置電源的陰極相連接，該外置電源的陽極和在銅錫電 φ 解質溶液內的固體銅和固體錫連接。發光器件放置在太陽 能電池的上部。把外置電源的輸出電流控制在0.5安培， 在太陽能電池受到光照2分鐘後，測得沈積在太陽能電池 的陰極表面的銅錫層厚度約爲0.01微米，測得沈積在太 陽能電池的陽極表面的銅錫層厚度約爲0.008微米。同時 測得該太陽能電池的光電轉換效率爲18.02%，其中它的 開路電壓爲620mV，電流密度爲3 6.9mA/cm2，串聯電阻 爲0.0051Ω’並聯電阻爲>1〇〇Ω，塡充因數爲78.8%。 φ 本發明特別適用於陰極和陽極分別在二個不同表面的 太陽能電池。 例如，大多數商業化的太陽能電池的陰極和陽極分別 在二個不同的表面。商業化太陽能電池的主受光面是它的 陰極表面’爲了減小電極的遮光面積，該太陽能電池的陰 極金屬導電電極是由許多柵線所組成。這種商業化太陽能 電池的陽極在其另外一個表面。本發明在應用於這種結構 的太陽能電池時’把其陰極表面和電解質溶液接觸，把其 陽極表面連接固體金屬並且不和電解質溶液接觸。這種電 -23- 201019491 化學反應的過程，很容易實現連續生產。 本發明也同時適用於陰極和陽極在同一表面的太陽能 電池。 爲了消除導電電極的遮光面積，提高太陽能電池的光 電轉換效率，可以把太陽能電池的陰極和陽極都放在太陽 能電池的主受光表面的反面。本發明在用於這種結構的太 陽能電池時，把該太陽能電池的含有陰極和陽極的一面和 電解質溶液接觸。在該太陽能電池的陽極和固體金屬之間 連接一個外置電源，並且把發光器件放置於太陽能電池的 上方。當發光器件發出光並且外置電源進行供電時，太陽 能電池的陰極和陽極同時發生電化學沈積金屬的反應，即 陰極和陽極的金屬導電電極同時生成。通過調節發光器件 的發光強度和外置電源的供電強度，可以調節在陰極和陽 極的沈積金屬的速率。 本發明不局限於上述特定實施例，在不背離本發明精 神及其實質情況下，熟悉本領域技術人員可根據本發明作 出各種相應改變和變形，但這些相應改變和變形都應屬於 本發明所附申請專利範圍保護範圍之內。 【圖式簡單說明】 圖1爲使用本發明的電化學沈積金屬的方法在太陽能 電池的陰極表面進行電化學反應以沈積金屬的示意圖。 【主要元件符號說明】 -24- 201019491201019491 IX. Description of the Invention [Technical Field] The present invention relates to a method of electrochemically depositing a metal, and more particularly to a method of electrochemically depositing a metal electrode on a cathode surface of a solar cell. [Prior Art] At present, the most common method for producing conductive electrodes of commercial solar cells is to use a screen printing method to apply silver paste on the cathode surface of the solar cell, apply aluminum paste on the surface of the anode, and then pass through a high temperature. After firing, a conductive cathode and an anode are simultaneously formed on the cathode and anode of the solar cell. The advantage of this method for generating a conductive electrode of a solar cell is that the method is simple and reliable, and is easy to be applied in mass production. However, the simple method of screen printing and co-firing to produce a solar cell conductive electrode limits the improvement of the photoelectric conversion efficiency of the solar cell. In order to ensure that the screen-printed paste can have better ohmic contact with the surface of the solar cell after co-firing, reducing the series resistance of the solar cell requires not only the design of a thicker metal sub-gate line (generally greater than 100 microns). ), and must also use a lower emitter block resistance design (typically 50 ohms per square). The design of the thicker metal sub-gate line reduces the effective working area of the solar cell, while the lower emitter block resistance design reduces the short-circuit current of the solar cell, which is the low photoelectric conversion efficiency of commercial solar cells. main reason. It is clear that one of the main measures to improve the photoelectric conversion efficiency of solar cells is to increase the sheet resistance of their emitters. However, after the solar cell emission -5-201019491 pole resistance is increased, if the screen printing paste and co-firing method continue, the contact resistance of the solar cell will be increased, thereby reducing the photoelectric conversion efficiency of the solar cell. Therefore, one of the problems that must be solved after increasing the sheet resistance of the solar cell emitter is to reduce the contact resistance between the metal conductive electrode and the solar cell. One way to solve the above problem is to use a selective diffusion method. The so-called selective diffusion method refers to generating two different tantalum sheet resistances in different regions of the emitter of the solar cell, that is, having a lower sheet resistance in the region where the metal conductive electrode _ is formed, and having a higher surface on the other light receiving surface. Square resistance. This method is designed to increase the short-circuit current of the solar cell and reduce the contact resistance between the metal wire and the solar cell. Therefore, the selective diffusion method is one of the main measures for improving the photoelectric conversion efficiency of a solar cell. However, the above screen printing and co-firing methods are difficult to apply to solar cells using the selective diffusion method. The main reason is that the screen printing method is difficult to align the metal paste on the area where the solar cell emitter has a lower square @ resistance. A common method for solving this alignment problem is to replace the above-described screen printing method by a method of chemically depositing a metal conductive electrode on the surface of a solar cell. A buried-gate solar cell is a method of chemically depositing metallic copper to form a metal conductive electrode on the emitter of a solar cell. The specific method is to cover the surface of the emitter having a large square resistance with a passivation film or an anti-reflection film, and after performing a deep diffusion on the passivation film by using a laser, the sheet resistance of the grooved region of the emitter surface is reduced. Finally, using the method of depositing metal from -6 - 201019491, a metal conductive electrode of a solar cell is generated in an emitter region having a lower sheet resistance. The process of chemically depositing copper is a relatively slow chemical process, which typically takes approximately 10 hours to reach the desired thickness of the metal conductive electrode. In order to prevent stress and adsorption problems due to too fast deposition speed, the rate of chemically deposited metal conductive electrodes is generally controlled to be less than 2 microns per hour. Φ There is another problem with the method of preparing a solar cell electrode by chemically depositing a metal. The service life of the chemically deposited metal solution is relatively short, and generally can only be used continuously after using several batches. Therefore, the method of chemically depositing metal generates a large amount of waste water when used in mass production. Since the discharged wastewater contains some organic matter that is relatively difficult to handle, the method of chemically depositing metal increases the production cost of the solar cell. Moreover, the solution of the chemically deposited metal is rather unstable, and the phenomenon of self-deposition of the metal is likely to occur, which affects normal production. In addition, the control of the process conditions for the chemical deposition of φ metal is also very demanding. For example, temperature control of chemically deposited copper solutions is critical. In order to reduce the possibility of self-depositing copper, in the case of chemical deposition of copper, not only air bubbling but also filtration is required. In order to keep the concentration of the solution stable, it is also required to continuously add a replenishing solution. The addition of replenisher must be very tightly controlled, too much will cause self-deposited copper, and too little will reduce the rate of copper deposition. In addition, the vast majority of chemically deposited copper is operated at temperatures above room temperature, such as greater than 5 (TC), which requires a large amount of energy to be supplied, further increasing production costs. Due to the longer reaction time, These 201019491 energy consumption is considerable in the production process. One of the ways to solve the above problems is to replace the chemical & metal method with electroplating. The advantages of electroplating methods, the speed of the metal deposition of the stomach Faster. After the electroplating method, the generation time of the solar electrode & conductive electrode can be shortened from the @10 of the chemical deposition metal to 1 hour. In general, after the electroplating method, the solar cell is prepared. The process of conducting the electrode can be completed in ten minutes. Another advantage of the method of replacing the chemically deposited metal by electroplating is that since the process of electrochemically depositing metal is much simpler than the process of chemically depositing metal, the operating range is Much larger, especially suitable for industrial production. For example, it does not require high temperature, generally The operation under temperature is beneficial to the production control and saves the cost of heating. The composition of the electrolyte used for electroplating is also very simple, so in general, the electrolyte can be used repeatedly for a long time. Further, the general The conductive electrode of the solar cell generated by the chemical deposition process is amorphous, and the metal conductive electrode of the electrochemically deposited solar cell is in a microcrystalline state, so the electrochemically deposited metal conductive electrode has better conductivity. The direct effect is that the electroplated metal electrode can reduce the loss of the current generated by the solar cell on the metal conductive electrode, thereby improving the conversion efficiency of the solar cell. The chemical deposition of the metal is very simple, for example, the pH of the electrolyte and the solution The composition change has little effect on the electroplating method, and the management of the solution is also very simple. Therefore, the electro-hydraulic method is very suitable for industrial production. More importantly, the gold battery of the solar cell generated by the electroplating method is a conductive electrode. Production cost is very low, for waste liquid Processes are also much simpler than chemically deposited metal wastes. However, there are certain difficulties in applying traditional plating methods to large-scale production of solar cells. The main problem is the contact between electroplated racks and solar cells. And the uniformity of the metal plated on the solar cell. The above electroplating rack is an important tool in the traditional electroplating operation, and one of the functions in the electroplating operation is to fix the solid object of the electroplated object to a certain extent. The position of the plating fixture is fixed to a certain range; the other function of the plating fixture is to conduct the current of the external power source to the object to be plated. In fact, before the metallization, the surface resistance of the solar cell is very large, Usually, the contact resistance between the plating hanger and the surface of the solar cell is large, and eventually the uniformity of the metal plated on the surface of the solar cell is poor. In addition, since the semiconductor material for preparing the solar cell is very brittle, the solar cell is In the process of loading and unloading the plating hanger, the chipping of the solar cell often occurs. • The usual solution to the above problems caused by mechanical and electrical contact between the solar cell and the plating rack is to immerse the solar cell in the electrolyte, using the energy generated by the solar cell under illumination, on the solar cell. A metal conductive electrode is deposited. Since the electric energy generated by the solar cell after the light is generated to generate the metal conductive electrode on the surface of the solar cell, the method does not need to rely on the traditional electric shovel to conduct the current of the external power source to the surface of the solar cell that needs to be plated, and solve the problem. Various problems caused by the use of plating hangers. However, this method of utilizing the solar cell itself to generate electric energy is also known. -9-201019491 There are also many defects in the method of depositing metal on the surface of a solar cell. First, in order to protect the metal on the anode surface of the solar cell, a DC power supply must be added. The anode of the DC power source is connected to a metal located in an electrolyte solution, the cathode of which is connected to the anode metal of the solar cell located in the electrolyte solution. Such a connection ensures that the metal on the anode of the solar cell will not be destroyed when metal is deposited on the cathode of the solar cell. In fact, the use of such a connection when depositing metal causes the cathode and anode of the solar cell to simultaneously deposit metal, resulting in an unnecessary increase in production cost. Another disadvantage of this method is that since the potential existing on the cathode surface of the solar cell is the sum of the potential generated by the solar cell and the potential of the external power source, the potential on the surface of the cathode of the solar cell depends not only on the solar cell. The potential also depends on the potential exerted by the external power source on the solar cell. Therefore, the uniformity of the metal plated on the surface of the solar cell depends not only on the uniformity of the illumination on the surface of the solar cell, but also on the uniformity of the potential applied to the solar cell by the external power source. For example, only very good contact of the entire surface is able to achieve a very uniform potential on the cathode surface of the solar cell. In fact, this uniform contact is difficult to achieve in industrial production. SUMMARY OF THE INVENTION In view of the above drawbacks in the prior art, one of the objects of the present invention is to provide a method for realizing electrochemical deposition of metal on the cathode surface of a solar cell by utilizing the characteristics that the solar cell generates an electric potential after receiving light. 10-201019491 Law. Further, it is another object of the present invention to provide a method of electrochemically depositing metal which ensures that metal is deposited only on the cathode surface of a solar cell. Still further, another object of the present invention is to provide a method of electrochemically depositing metal on the cathode surface of a solar cell capable of effectively controlling the rate of metal deposition. Φ A final object of the present invention is to provide a method for depositing metal on the cathode surface of a solar cell suitable for mass production. In order to achieve the above object, the present invention provides a method for electrochemically depositing a metal electrode of a solar cell, comprising the steps of: contacting a cathode-containing surface of a solar cell with an electrolyte solution; connecting an anode of the solar cell to a solid metal; using a light source Illuminating the main light-receiving surface of the solar cell; the metal ions in the electrolyte solution receive electrons generated on the surface of the solar cell cathode to form a metal and deposit on the cathode surface of the solar cell, and the solid metal provides the anode of the solar cell After the electrons, metal ions are generated and dissolved in the electrolyte solution. The solar cell is not in contact with the electrolyte solution except for the surface containing the cathode. The surface of the solar cell in contact with the electrolyte solution contains only a cathode. The surface of the solar cell in contact with the electrolyte solution may contain both a cathode and an anode. 11 - 201019491 The electrolyte solution includes metal ions, acid groups, water, and additives. The electrolyte solution contains at least one or more metal ions. The electrolyte solution contains at least one or more acid groups. The electrolyte solution also includes one or more additives. The main light-receiving surface is a surface of the solar cell in contact with the electrolyte solution or a surface thereof that is not in contact with the electrolyte solution. In the step of illuminating, the source of illumination is natural light or light emitted by an illumination device. In the step of performing the illumination, the light is directly irradiated onto the surface of the solar cell or transmitted through the electrolyte or other medium to be irradiated onto the surface of the solar cell. The anode of the solar cell and the solid metal are electrically connected by a wire. The solid metal consists of at least one metal or alloy. At least one surface of the solid metal contacts the electrolyte solution. The method also includes the step of connecting an external power source between the anode of the solar cell and the solid metal. @ The external power source is a DC power source, wherein the cathode of the DC power source is connected to the anode of the solar cell, and the anode of the DC power source is connected to the solid metal. The output power of the DC power supply is not less than zero. The solid metal has the same composition as the metal component deposited on the surface of the cathode of the solar cell. The solar cell is fixed above the electrolyte solution. The solar cell moves in the horizontal direction. -12- 201019491 In the process of electrochemically depositing metal of the present invention, metal ions can only be deposited on the cathode of the solar cell, thereby fundamentally solving the problem of battery efficiency degradation caused by metal deposition at the anode. At the same time, the use of any electrical contact to damage the solar cell and the possibility of uneven deposition of the metal are avoided. Another advantage of the present invention is that the other surface of the solar cell is not in contact with the electrolyte solution, so there is no need to add an external power source to protect the metal of the other surface of the solar cell. Thereby, the potential of the surface of the solar cell can be changed from zero and can be effectively controlled to control the electrochemical reaction rate of the cathode surface of the solar cell. Another important advantage of the present invention is that the potential of the solar cell is very uniform throughout the surface due to the uniformity of the illumination intensity, so that the metal deposited on the cathode surface of the entire solar cell is also very uniform. Yet another advantage of the present invention is the ability to achieve self-alignment. This advantage is particularly advantageous for the preparation of solar cells having a selective diffusion structure. [Embodiment] Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic illustration of electrochemical reaction of a cathode surface of a solar cell to deposit a metal using the method of electrochemically depositing metal of the present invention. As shown, the apparatus for electrochemically depositing metal of the present invention is mainly used for an electrolyte solution tank 10, an electrolyte solution 20, a solar cell 30, a metal wire 40, a metal block 50, and a light-emitting device 60. -13- 201019491 The main function of the electrolyte solution tank ίο of the present invention is to hold the electrolyte solution 20. In the case where the main light-receiving surface of the solar cell 30 is its cathode surface, the other function of the electrolytic cell 10 of the present invention is to allow light emitted from the illuminating device 60 to be transmitted to the main light-receiving surface of the solar cell 30. Thus, the electrolyte bath 10 of the present invention can be generally made of a transparent and corrosion-resistant material such as quartz, glass, transparent organic material or the like. When the main light receiving surface of the solar cell does not contain its cathode, that is, when the main light receiving surface and the cathode surface are respectively two sides of the solar cell, the light emitting device should be placed above the solar cell to directly illuminate the emitted light. On the upper surface of the solar cell. The electrolyte solution 20 in the electrolytic solution tank 10 of the present invention is mainly composed of metal ions and acid radicals such as copper sulfate, nickel chloride and the like. The electrolyte solution 20 may contain only one metal ion or a plurality of metal ions depending on the requirements of the deposited metal. Also, depending on the requirements of the deposited metal, the electrolyte solution 20 may contain only one acid group or a plurality of acid groups such as sulfate and nitrate. In order to reduce the stress of the deposited metal and improve the flatness of the deposited gold crucible, appropriate additives may be added to the electrolyte solution 20 depending on the electrolyte solution and the method of electrochemically depositing the metal. An important technical feature of the present invention is that the solar cell 30 has only one surface containing the cathode in contact with the electrolyte solution 20 and the other surface is not in contact with the electrolyte solution 20. For the simplicity of industrial production, more than 90% of commercial solar power 201019491 two surfaces of the pool are cathode and anode. The method of the invention is therefore particularly suitable for depositing metals on such commercial solar cells. When the method of the present invention is applied to the above-described commercial solar cell, since its anode is on the reverse side of its cathode and is not in contact with the electrolyte solution, it is not necessary to connect an external power source to protect the metal on the anode of the solar cell. As shown in Fig. 1, the solid metal 50 and the solar cell 30 are electrically connected by a wire 40. In general, the main component φ of the solid metal 50 is the same as the metal component to be deposited on the cathode surface of the solar cell 30. The solid metal 50 may be a single component metal or an alloy composed of one or more metals. The solid metal 50 can be placed at any position within the electrolytic cell 10 while having good contact with the electrolyte solution 20. When the cathode of the solar cell 30 is the main light receiving surface, the position at which the solid metal 50 is placed should not affect the light emitted from the light emitting device 60 to be projected onto the surface of the solar cell 30. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 illustrates the complete reaction process for electrochemical deposition of a metal electrode on the cathode surface of a solar cell using the method of the present invention. Unlike the conventional electroplating method, the electrochemical reaction of the present invention can realize the electrochemical reaction by using the electric energy generated by the solar cell itself without supplying electric energy from the outside. In FIG. 1, the light emitting device 60 is located below the electrolytic cell 10. The position at which the light-emitting device 60 is located depends on the structure of the solar cell 30. When the cathode of the solar cell 30 is the main light receiving surface of the solar cell, the light emitted by the light emitting device 60 passes through the transparent electrolytic cell 10, passes through the electrolyte solution 20, and is irradiated onto the lower surface of the solar cell 30. -15- 201019491 Cathode surface. A solar cell is a device that converts light energy into electrical energy. When the solar cell is exposed to light, a negative potential is generated at the surface of the emitter, the cathode. Therefore, the above illumination causes the solar cell 30 to emit electrons after generating a negative potential. The metal ions in the electrolyte solution 20 are moved toward the cathode by the negative potential, and after accepting electrons on the cathode surface of the solar cell 30, metal atoms are generated and deposited on the cathode surface of the solar cell 30. At the same time, the solid metal 50 in the electrolyte solution 20, through the conductive line 40, under the action of the positive potential of the anode of the solar cell 30, continuously loses electron-forming metal ions and dissolves into the electrolyte solution 20 to maintain the electrolyte solution 20 The concentration of metal ions is stable. The result is an electrochemical reaction process that requires no external power supply. Unlike the electroplating process in which an external power source needs to be connected, the above-described process of electrochemically depositing metal of the present invention does not require an external power source to be connected, but the entire electrochemical reaction is realized by the potential generated by the solar cell 30 itself after illumination. Metal ions can only be deposited on the cathode of the solar cell 30 during the process. This feature is of great importance in the industrial production of solar cells. If an external power source is connected to achieve an electrochemical reaction, the unprotected cathode and anode on the surface of the solar cell will deposit metal, causing a short circuit of the solar cell and reducing the photoelectric conversion efficiency of the solar cell. In the method of the present invention, even if there is an exposed anode surface, since the solar cell can only receive electrons at its anode and cannot release electrons after receiving the light, the metal cannot be deposited on the anode of the solar cell, thereby -16- 201019491 Fundamentally solved the problem of battery efficiency degradation caused by anode short circuit. At the same time, since the thickness of the solar cell sheet is generally about 200 micrometers, any local physical contact is liable to cause chipping, and the electrochemical deposition metal process of the present invention may not require an external power source to be connected. The process can be used without any electrical contact' thereby avoiding the possibility of damaging the solar cell. A Further, since the resistance of the cathode surface of the solar cell is generally larger than w, if the external electrical contact is caused, the potential unevenness at the cathode surface of the solar cell is caused, eventually resulting in unevenness of the metal deposited on the surface of the solar cell. In the electrochemical reaction of the present invention, as long as the light intensity is uniform on the surface of the solar cell, the potential generated by the solar cell is uniform over the entire surface thereof, i.e., the metal deposited on the surface thereof is uniform. On the other hand, in the electrochemical reaction process of the present invention, the surface of the cathode containing the solar energy battery is in contact with the electrolyte solution, and the other surface of the solar cell is not in contact with the electrolyte solution, so that it is not necessary to use an external power source to protect the solar cell. A surface of metal. Thus, the potential of the surface of the solar cell can be changed from zero, and the electrochemical reaction rate on the cathode surface of the solar cell can be well controlled, and the rate of electrochemical deposition of the metal can be arbitrarily changed by changing the light intensity. The metal deposited on the cathode surface of the solar cell produced by the method of the present invention is very uniform. This is because the potential generated by the solar cell is proportional to the intensity of the light it receives, as long as the strip is -17-201019491, the potential of the solar cell is very uniform over the entire surface, independent of the anode metal block. The influence of the position, shape and size. A uniform potential produces a uniform electrochemical reaction rate, so that a uniform metal deposit can be obtained. The method of the present invention is particularly advantageous for the preparation of solar cells having a selective diffusion structure. In order to reduce the reflectivity of the solar cell, an antireflection film having a reduced reflectance is generally plated on the surface having a high square resistance. This layer of anti-reflection film acts as a mask during the electrochemical deposition of the metal of the present invention, preventing electrons generated by the cathode of the solar cell from coming into contact with metal ions in the electrolyte solution. On the low-profile resistance surface subjected to selective diffusion, the mask is not protected, and the electrons generated by the solar cell are in contact with the metal ions in the electrolyte solution, and an electrochemical reaction occurs to form a metal conductive electrode on the surface. The process of electrochemically depositing metals of the present invention may be either interstitial or continuous. In the process of electrochemically depositing metal in the gap, the solar cell 30 of the present invention is fixed above the electrolyte solution 20, and the surface containing the cathode is in contact with the electrolyte solution 20. When the solar cell 30 receives the light emitted by the light-emitting device 60, the metal ions in the electrolyte solution 20 receive electrons on the cathode surface of the solar cell, generate metal and deposit on the cathode surface of the solar cell. In the process of continuously electrochemically depositing metal, the solar cell 30 of the present invention moves in the horizontal direction. The way to move the solar cell 30 can be a roller or a moving stand. For example, the solar cell 30 can be placed on a set of rollers on the 201019491, and the surface containing the cathode is in contact with the electrolyte solution 20 underneath. When the set of rollers rotates in a certain direction, the solar cell 30 is on the set of rollers. Moving in this direction, a process of continuously electrochemically depositing metal is achieved. The following are a few specific examples of using the method of the present invention. First, the first step of the first embodiment is to make a traditional solar cell: φ P-type ruthenium is subjected to texturing, diffusion, edge etching, N-type surface tantalum nitride film, P-type surface screen printing aluminum paste, N The screen surface printing silver paste, after sintering, the photoelectric conversion efficiency of the solar cell was 16.5 7%, wherein its open circuit voltage, current density, series resistance, parallel resistance and charging factor were respectively 625 mV; 35.3 mA / Cm2; 0.0075 Ω; 1 3 · 1 1 Ω ; 7 5 . 1 %. The second step is to prepare an electrolyte solution: Preparation of a copper electrolyte solution: 200 g of copper sulfate, 120 g of sulfuric acid, and 4.5 ml of brightener VF100 are uniformly dissolved in 1 liter of water. Preparation of tin electrolyte solution: 50 g of stannous sulfate, 60 g of sulfuric acid, 48 g of phenolsulfonic acid, and 2.4 g of cresol were uniformly dissolved in 1 liter of water. The third step is electrochemical deposition of the metal: the cathode surface of the solar cell is contacted with the above copper electrolyte solution, and the anode of the solar cell is connected to the solid copper in the copper electrolyte solution. The light emitting device is placed in the lower portion of the transparent electrolyte solution bath. After the solar cell was exposed to light for 15 minutes, the thickness of the copper layer deposited on the cathode conductive electrode of the solar cell was measured to be about 10 μm. -19- 201019491 Then, the cathode of the solar cell obtained by the above steps is brought into contact with the above tin electrolyte solution, and the anode of the solar cell is connected with the solid tin in the tin electrolyte solution. The light emitting device is placed in the lower portion of the transparent electrolyte solution bath. After the solar cell was exposed to light for 1 minute, the thickness of the tin layer deposited on the cathode conductive electrode of the solar cell was measured to be about 0.01 μm. At the same time, the photoelectric conversion efficiency of the solar cell was increased to 16.94%, wherein its open circuit voltage was 626 mV, the current density was 35.2 mA/cm2, the series resistance was 0.0045 Ω, the parallel resistance was 49.41 Ω, and the 塡 charging factor was A 7 . 6.9%. Second, the second embodiment of the first step is to make a buried grid battery: P-type enamel sheet is subjected to texturing, shallow diffusion, edge etching, oxidation, laser engraved gate groove on the N-type surface, in the buried gate Deep diffusion, sputtering aluminum on the P-type surface, then aluminum sintering, electroless nickel plating in the buried gate trench, and then nickel sintering to form a nickel-niobium alloy. The second step is to prepare the electrolyte solution: @錬 Electrolyte solution preparation: 150 g of nickel sulfate, 8 g of sodium chloride, 30 g of boric acid, 40 g of anhydrous sodium sulfate, uniformly dissolved in 1 liter of water in a beryllium copper electrolyte solution Formulation: 200 g of copper sulfate, 120 g of sulfuric acid, and 4.5 ml of brightener VF100 were uniformly dissolved in 1 liter of water. Preparation of copper-zinc alloy electrolyte solution: 75 g of cuprous cyanide, 9 g of zinc cyanide, 55 g of sodium cyanide, 10 g of sodium carbonate, and 4 g of sodium fluoride were uniformly dissolved in 1 liter of water. -20- 201019491 The third step is electrochemical deposition of a buried gate battery cathode metal: the cathode surface of the solar cell is contacted with the above nickel electrolyte solution, and the anode of the solar cell is connected to the solid nickel in the nickel electrolyte solution. The light emitting device is placed in the lower portion of the transparent electrolyte solution tank. After the solar cell was exposed to light for 5 minutes, the thickness of the nickel layer deposited in the buried trench of the solar cell was measured to be about 0.1 μm. Further, the cathode surface of the solar cell subjected to the above steps is brought into contact with the above copper φ electrolyte solution, and the anode of the solar cell is connected to solid copper in the copper electrolyte solution. The light emitting device is placed in the lower portion of the transparent electrolyte solution bath. After the solar cell is exposed to light for 20 minutes, the thickness of the copper layer deposited in the buried gate of the solar cell is measured to be about 15 μm. Then, the cathode surface of the solar cell subjected to the above steps is contacted with the copper-zinc alloy electrolyte solution. The anode of the solar cell is connected to a solid copper-zinc alloy in a copper-zinc alloy electrolyte solution. The light emitting device is placed in the lower portion of the transparent electrolyte solution tank. After the solar cell was exposed to light for 2 φ minutes, the thickness of the copper-zinc alloy deposited in the buried gate of the solar cell was measured to be about 0.101 μm. At the same time, the photoelectric conversion efficiency of the solar cell was measured to be 17.53%, wherein its open circuit voltage was 620 mV, the current density was 35.7 mA/cm2, the series resistance was 0.0040 Ω, the parallel resistance was > 100 Ω, and the enthalpy factor was 79.2%. III. Third Embodiment The first step is to fabricate a full-back conductive electrode solar cell: velvet on a ruthenium-type ruthenium, Ν-type diffusion, oxidation, using a photoresist as a mask to open the Ρ-type electrode contact region, Ρ type Deep expansion, using photoresist as the mask - 201119491 as a mask to open the N-type electrode contact area, electroless nickel plating in the electrode contact area, and then nickel sintering to form a nickel-niobium alloy. The second step is to prepare an electrolyte solution: Preparation of a nickel electrolyte solution: 150 g of nickel sulfate, 8 g of sodium chloride, 30 g of boric acid, 40 g of anhydrous sodium sulfate, and uniformly dissolved in 1 liter of water. Preparation of copper electrolyte solution: 200 g of copper sulfate, 120 g of sulfuric acid, and 4.5 ml of brightener VF100 were uniformly dissolved in 1 liter of water. Copper tin electrolyte solution: 20 g of cuprous cyanide, 30 g of sodium stannate, 20 g of sodium cyanide, and 10 g of sodium hydroxide were uniformly dissolved in 1 liter of water. The third step is electrochemical deposition of a full-back conductive electrode solar cell electrode: contacting the surface of the conductive electrode of the solar cell with the nickel electrolyte solution, and the anode of the solar cell is coupled to a cathode of an external power source, the external power source The anode is connected to solid nickel in a nickel electrolyte solution. The light emitting device is placed on the upper portion of the solar cell. The output current of the external power source is controlled at 1 ampere, and after the solar cell is exposed to light for 5 minutes, the thickness of the nickel layer deposited on the cathode surface of the solar cell is measured to be about 1 μm, and the deposition is measured on the anode surface of the solar cell. The thickness of the nickel layer is approximately 0.08 microns. And the surface of the conductive electrode of the solar cell subjected to the above steps is contacted with the copper electrolyte solution, and the anode of the solar cell is coupled with the cathode of an external power source, and the anode of the external power source is connected with the solid copper in the copper electrolyte solution. . The light emitting device is placed on the upper portion of the solar cell. The output current of the external-22-201019491 power supply was controlled at 1.5 amps. After the solar cell was exposed to light for 20 minutes, the thickness of the copper layer deposited on the cathode surface of the solar cell was measured to be about 15 μm, and the deposition was measured in solar energy. The copper layer thickness of the anode surface of the cell is about 12 microns. Then, the surface of the conductive electrode of the solar cell subjected to the above steps is contacted with the copper-tin electrolyte solution, and the anode of the solar cell is connected to the cathode of an external power source, and the anode of the external power source and the copper-iron φ solution The solid copper in the solution is connected to the solid tin. The light emitting device is placed on the upper portion of the solar cell. The output current of the external power source was controlled at 0.5 ampere. After the solar cell was exposed to light for 2 minutes, the thickness of the copper tin layer deposited on the cathode surface of the solar cell was measured to be about 0.01 μm, and the deposition was measured on the anode surface of the solar cell. The copper tin layer has a thickness of about 0.008 microns. At the same time, the photoelectric conversion efficiency of the solar cell was measured to be 18.02%, wherein its open circuit voltage was 620 mV, the current density was 3 6.9 mA/cm 2 , and the series resistance was 0.0051 Ω 'parallel resistance was > 1 〇〇 Ω, the 塡 因数 factor It is 78.8%. φ The invention is particularly applicable to solar cells in which the cathode and anode are respectively on two different surfaces. For example, most commercial solar cells have cathodes and anodes on two different surfaces. The main light-receiving surface of a commercial solar cell is its cathode surface. In order to reduce the light-shielding area of the electrode, the cathode metal-conducting electrode of the solar cell is composed of a plurality of gate lines. The anode of this commercial solar cell is on its other surface. The present invention is applied to a solar cell of such a structure by bringing its cathode surface into contact with an electrolyte solution, connecting its anode surface to a solid metal, and not in contact with an electrolyte solution. This process of chemical reaction -23-201019491 makes it easy to achieve continuous production. The invention is also applicable to solar cells having the same surface of the cathode and the anode. In order to eliminate the light-shielding area of the conductive electrode and improve the photoelectric conversion efficiency of the solar cell, the cathode and the anode of the solar cell can be placed on the opposite side of the main light-receiving surface of the solar cell. The present invention relates to a solar cell having a cathode and an anode in contact with an electrolyte solution. An external power source is connected between the anode of the solar cell and the solid metal, and the light emitting device is placed above the solar cell. When the light-emitting device emits light and an external power source supplies power, the cathode and the anode of the solar cell simultaneously react with the electrochemically deposited metal, that is, the metal conductive electrodes of the cathode and the anode are simultaneously generated. The rate of deposition of metal at the cathode and the anode can be adjusted by adjusting the luminous intensity of the light-emitting device and the power supply of the external power source. The present invention is not limited to the specific embodiments described above, and various changes and modifications can be made by those skilled in the art without departing from the spirit and scope of the invention. Within the scope of protection of the patent application scope. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic view showing an electrochemical reaction of a cathode surface of a solar cell to deposit a metal using the method of electrochemically depositing metal of the present invention. [Main component symbol description] -24- 201019491
參 1 〇 ·’電解質溶液槽 2 0 :電解質溶液 3 〇 =太陽能電池 4 0 :金屬導線 5 〇 :金屬塊 60 :發光器件 -25-Reference 1 〇 ·' Electrolyte solution tank 2 0 : Electrolyte solution 3 〇 = Solar battery 4 0 : Metal wire 5 〇 : Metal block 60 : Light-emitting device -25-