TWI596790B - 光伏電力元件及其製造方法 - Google Patents

光伏電力元件及其製造方法 Download PDF

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TWI596790B
TWI596790B TW103110124A TW103110124A TWI596790B TW I596790 B TWI596790 B TW I596790B TW 103110124 A TW103110124 A TW 103110124A TW 103110124 A TW103110124 A TW 103110124A TW I596790 B TWI596790 B TW I596790B
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小林英治
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Description

光伏電力元件及其製造方法 發明領域
本發明乃有關於矽系薄膜異質接面太陽電池中使用之光伏電力元件,特別是有關於更加提高發電效率且連薄型亦可適用之光伏電力元件及其製造方法。
發明背景
現今為對抗地球暖化,全球倡議大幅減少CO2排放量,光發電裝置(太陽能板)因身為不產生CO2等氣體之潔淨能源而持續擴大普及。其中,又以設有發電效率高之異質接面之光發電元件的光發電裝置備受矚目。該光發電裝置具有數個如圖8所示之光發電元件(光伏電力元件)71。光發電元件71於n型單晶矽基板(c-Si)72之一面(上面)隔著本質非晶質系矽層(i層)73設置p型非晶質系矽薄膜層74,並於n型單晶矽基板(c-Si)72之另一面(下面)隔著本質非晶質系矽層(i層)75設置n型非晶質系矽薄膜層76,p型非晶質系矽薄膜層74之上及n型非晶質系矽薄膜層76之下分別具有透明導電氧化物(Transparent Conductive Oxide)78、79,並有梳狀集電極(指狀電極)80、81與其等接合。
而且,為更加提高光接收效率,乃如圖9所示對沿(100)面切片而成之n型單晶矽基板72進行異向性蝕刻加工,形成有在(111)面定向之多數錐狀凹凸部83。特別是專利文獻1中記載,藉由圓滑形成錐狀凹凸部83之凹谷84部分,可降低經電漿CVD法形成並覆蓋n型單晶矽基板72之本質非晶質系矽層73之膜厚不均性,且可提昇光伏電力元件之效率(具體上為FF值)。
又,專利文獻1(第9頁第20~31行)亦揭示,於異向性蝕刻時使用2重量%之氫氧化鈉與用以抑制氣泡產生之異丙醇,形成深度為1~10μm左右之錐體。但記載了異丙醇會氣化故須注滿,因對作業環境有惡劣影響而須嚴加控管。此外,異丙醇價格高昂,因此成本增加。由於上述事態,故專利文獻1中對於具有具1~10μm左右深度之錐狀凸部之光伏電力元件完全未揭示其作用及性能。
專利文獻1中記載,將異丙醇改為使用界面活性劑(例如日本油脂股份有限公司製SINTREX),並使用於1.5重量%之NaOH水溶液中添加有1重量%之上述界面活性劑的蝕刻液,經30分鐘之蝕刻時間,製造具有寬度5μm且深度5μm之錐狀凹凸部並具有優異光侷限效果之矽基板。並記載隨後將矽基板浸漬於混合有氫氟酸與硝酸之水溶液中進行等向性蝕刻,賦予凹凸部之凹谷部分以0.1μm以上之圓度後,藉由電漿CVD法並使用矽烷氣體(SiH4),堆積成膜厚50~200埃之本質非晶質系矽層。
先前技術文獻 專利文獻
專利文獻1:國際公開第98/43304號
非專利文獻
非專利文獻1:「非晶質/晶質矽異質接面於界面之特性(Properties of interfaces in amorphous/crystalline silicon heterojunctions)」Sara Olibet et al., Phys. Status Solidi A, 1-6 (2010)
發明概要
本發明人實際驗證專利文獻1之技術後得知,不僅是FF值,連開路電壓Voc值亦可提高。因此,本發明人基於該等技術內容,在不使用異丙醇等有害有機溶劑下形成錐狀之凹凸部,並以其對角線長度為參數實驗求出與發電效率之關係。
進一步又得知,若將錐狀凹凸部之形狀變大,則需更厚之矽基板,而有致使形成在透明導電氧化物上之梳狀集電極所用之金屬糊(通常為銀糊)之使用量增加的問題。
關於非專利文獻1容後另述。
本發明乃有鑑於所述事態而完成者,其目的在於提供一種在不使用有害人體又價昂之有機溶劑下對矽基板進行蝕刻而形成有錐狀凹凸部、並提高了發電效率之光伏電力元件及其製造方法。
承襲前述目的之第1發明之光伏電力元件具備矽基板及非晶質系薄膜,該矽基板係經由異向性蝕刻而於表面形成有多數錐狀凹凸部者,該非晶質系矽薄膜係藉由化學氣相沉積法而形成於前述錐狀凹凸部上者;而且,按下述算式定義,形成前述錐狀凹凸部之錐體的對角線平均長度係小於5μm;對角線之平均長度=(2×視野範圍之面積/視野範圍之錐體的頂點數)0.5
第1發明之光伏電力元件中,並未進行於凹凸部之凹谷部積極形成R之蝕刻處理。
另,就專利文獻1所記載之寬度5μm且深度5μm之錐狀凹凸部而言,此處所稱寬度應指邊長,此時對角線之平均長度約7μm。
第2發明之光伏電力元件係基於第1發明之光伏電力元件,其於前述矽基板之溫度超過180℃且在220℃以下之狀態下藉由化學氣相沉積法積層非晶質系矽薄膜,而該非晶質系矽薄膜至少與前述矽基板直接接合。
第3發明之光伏電力元件係基於第1、第2發明之光伏電力元件,其中前述矽基板之厚度於70~120μm之範圍。
第4發明之光伏電力元件係基於第1至第3發明之光伏電力元件,其於表面形成有指狀電極,且該指狀電極之厚度於1~5μm之範圍。
第5發明之光伏電力元件係基於第1至第4發明之 光伏電力元件,其中前述對角線之平均長度於2~4μm之範圍。
第6發明之光伏電力元件係基於第1至第5發明之光伏電力元件,其開路電壓為720mV以上。
第7發明之太陽電池模組係具備有如第1至第6發明之光伏電力元件。
且,第8發明之太陽電池系統係具備有如第7發明之太陽電池模組。
第9發明之光伏電力元件之製造方法,所製造之光伏電力元件係具備經由異向性蝕刻而於表面形成有多數錐狀凹凸部之矽基板、以及藉由化學氣相沉積法而形成於前述錐狀凹凸部上之非晶質系矽薄膜;該製造方法具有一蝕刻步驟,係對蝕刻前矽基板進行前述異向性蝕刻而獲得前述矽基板,該異向性蝕刻不使用異丙醇,而是使用鹼、含有醇衍生物及界面活性劑中至少1種之添加劑、與水之混合液;且,按下述算式定義,形成前述錐狀凹凸部之錐體的對角線平均長度係小於5μm;對角線之平均長度=(2×視野範圍之面積/視野範圍之錐體的頂點數)0.5
而且,第10發明之光伏電力元件之製造方法係基於第9發明之光伏電力元件之製造方法,其中前述混合液之鹼濃度例如以NaOH換算計為0.2~2質量%(小於1質量%為佳),且前述蝕刻步驟係將前述蝕刻前矽基板浸漬於前述混合液中10~20分鐘;此外該製造方法更具有一清洗步驟,以 進行前述矽基板之清洗處理。
其中,藉由在鹼性溶液(混合液)中添加界面活性劑,可防止蝕刻時產生之矽碎片或反應生成物再附著於矽基板,使矽基板表面產生微細粗糙。又,藉由在鹼性溶液(混合液)中添加醇衍生物(由醇衍生而得之化合物,有羧酸、醛、酯等。宜使用對人體無害者),可適度抑制矽基板表面之蝕刻反應,並可於矽基板表面有效形成多數錐狀凹凸部。
氫氧化鈉或氫氧化鉀等鹼性溶液之濃度宜設為0.2~2質量%(按氫氧化鈉換算計宜小於1質量%),添加劑之濃度宜設為0.05~0.5質量%,處理溫度宜設為75~90℃。蝕刻時間長則生產效率低,因此宜調整鹼試劑(鹼)與添加劑之濃度比使蝕刻處理在10~20分鐘左右結束。例如,於短時間內形成既小且密的錐狀凹凸部時,只要降低鹼試劑之濃度並提高添加劑之濃度即可。
繼之,進行蝕刻處理後,通常宜以純水或與其相當之洗淨劑施以洗淨處理。另,在形成凹凸部之前述蝕刻步驟前,宜2階段進行去除損傷層之蝕刻、即蝕刻處理。舉例言之,首先令鹼濃度為5質量%以上以提高蝕刻速度而增強等向性,並去除基板表面因矽基板切片步驟所生之損傷層。去除損傷層後,宜進行增強等向性而形成凹凸部之前述蝕刻步驟。
藉由本發明之光伏電力元件及其製造方法,可提供發電效率(Pmax)高於習知光伏電力元件之光伏電力元 件,其凹凸部之對角線長度小於習知,故所需矽基板之製造時間短,可提高生產效率。
進而,因蝕刻量少,故可使用較薄之矽基板,所需矽基板之材料少。
而且,凹凸部之深度(高度)亦縮小,故形成於光伏電力元件表面之集電極的厚度亦薄,可減少集電極材料(例如銀)之使用量。
10‧‧‧光伏電力元件
11‧‧‧n型單晶矽基板(矽基板)
12‧‧‧本質非晶質系矽薄膜層
13‧‧‧p型非晶質系矽薄膜層
14‧‧‧本質非晶質系矽薄膜層
15‧‧‧n型非晶質系矽薄膜層
16、17‧‧‧透明導電氧化物
18、19‧‧‧梳狀集電極(指狀電極)
71‧‧‧光發電元件(光伏電力元件)
72‧‧‧n型單晶矽基板(c-Si)
73‧‧‧本質非晶質系矽層(i層)
74‧‧‧p型非晶質系矽薄膜層
75‧‧‧本質非晶質系矽層(i層)
76‧‧‧n型非晶質系矽薄膜層
78、79‧‧‧透明導電氧化物
80、81‧‧‧梳狀集電極(指狀電極)
83‧‧‧錐狀凹凸部
84‧‧‧錐狀凹凸部之凹谷
圖1係本發明一實施形態之光伏電力元件之截面圖。
圖2係錐狀凹凸部之對角線長度之說明圖。
圖3係對角線平均長度為7μm之業經蝕刻之矽基板的顯微鏡照片。
圖4係對角線平均長度為5μm之業經蝕刻之矽基板的顯微鏡照片。
圖5係對角線平均長度為4μm之業經蝕刻之矽基板的顯微鏡照片。
圖6係對角線平均長度為3μm之業經蝕刻之矽基板的顯微鏡照片。
圖7係對角線平均長度為2μm之業經蝕刻之矽基板的顯微鏡照片。
圖8係習知例之光伏電力元件之截面圖。
圖9係習知例之光伏電力元件之局部放大截面圖。
用以實施發明之形態
繼之,參照附圖說明本發明經具體化後之實施形態。
如圖1所示,本發明一實施形態之光伏電力元件10,係構成非晶質系矽薄膜異質接合太陽電池,於中央具有n型單晶矽基板(c-Si,以下僅稱矽基板)11,其上面隔著本質非晶質系矽薄膜層(i層)12設置p型非晶質系矽薄膜層13,並於矽基板11之下面隔著本質非晶質系矽薄膜層(i層)14設置n型非晶質系矽薄膜層15,p型非晶質系矽薄膜層13之上及n型非晶質系矽薄膜層15之下分別具有透明導電氧化物(Transparent Conductive Oxide)16、17,且各於表面具有梳狀集電極(指狀電極)18、19。
矽基板11之上下表面以化學方法經由異向性蝕刻施有凹凸處理,以使光漫反射所致之光侷限更為有效。即,藉由將已沿(100)面切片之蝕刻前矽基板(損傷層業經去除)浸漬於例如0.2~2質量%(較佳為0.5~1.5質量%,小於1質量%更佳)之氫氧化鈉或同等之含氫氧化鈉鹼性水溶液(混合液),可形成多數錐狀凹凸部。該凹凸部係因(111)面之蝕刻速度明顯小於其他結晶方位而產生。混合液之鹼濃度例如超過2質量%且高達5質量%時,會推進等向性蝕刻,而難以形成多數錐狀凹凸部。
此時,若於蝕刻液(混合液)使用異丙醇水溶液,會如前述因異丙醇揮發而使作業環境惡化,故使用含醇衍生物及界面活性劑中至少1種的添加劑而不使用異丙 醇水溶液。醇衍生物及界面活性劑之沸點宜為100℃以上。該添加劑可使用例如市售之GP solar GmbH之「ALKA-TEX」等。本實施形態係使用GP solar GmbH之「ALKA-TEX」系列中之「ALKA-TEX ZERO」。即,蝕刻液可使用氫氧化鈉或氫氧化鉀等鹼、「ALKA-TEX ZERO」(含醇衍生物及界面活性劑中至少1種之添加劑的一例)及水之混合液。又,宜將蝕刻前矽基板浸漬於混合液中10~20分鐘後,再對形成有凹凸部之矽基板11進行洗淨處理。
藉由控制該蝕刻液之濃度與蝕刻時間,即可如圖3~圖7依序所示形成大小不同之錐狀凹凸部A~E。具體順序為(1)H2O沖洗(室溫)、(2)NaOH(5質量%、85℃)、(3)H2O沖洗(室溫)、(4)NaOH/ALKA-TEX ZERO(表1)、(5)H2O沖洗(室溫)、(6)HCl/H2O2/H2O(體積比1:1:5、80℃)、(7)H2O沖洗(室溫)、(8)HF/H2O(5質量%、室溫)、(9)H2O沖洗(室溫)。矽基板之切出厚度(蝕刻前矽基板之厚度)為180μm,蝕刻後之矽基板之完工厚度為165μm。另外,可將蝕刻前矽基板之厚度變薄,並令完工後之矽基板之厚度(平均厚度)為70~120μm。藉此可提供更薄且高經濟性之光伏電力元件。
其中,如圖2所示,將形成錐狀凹凸部A~E之錐體的對角線平均長度L定義為(2×視野範圍之面積/視野範圍之錐體的頂點數)0.5時,可形成L為7μm(A)、5μm(B)、4μm(C)、3μm(D)、2μm(E)之錐狀凹凸部。在此,(A)~(E)係對應圖3~圖7所示之係基板。
另,圖3~圖7係使用OLYMPUS公司製雷射顯微鏡OLS4000測得之雷射顯微鏡影像。前述對角線平均長度L之定義中,每1測定之雷射顯微鏡影像之視野範圍為128μm×128μm。數算前述視野範圍內之錐體頂點數,算出形成錐狀凹凸部之錐體的對角線平均長度L。實際上是數算矽基板中央附近1處與矽基板中央往4個角之間的4處、即共計5處雷射顯微鏡影像之錐體頂點數,算出對角線平均長度L。
又,蝕刻液之濃度、蝕刻時間、溫度如表1。
其次,藉由電漿CVD法(化學氣相沉積法之一例) 於該等形成有錐狀凹凸部A~E之矽基板11之表面,形成非晶質系矽薄膜(即,本質非晶質系矽薄膜層(i層)12、p型非晶質系矽薄膜層13、本質非晶質矽薄膜層(i層)14、n型非晶質系矽薄膜層15)。在電漿CVD法之原料氣體方面,譬如於形成p型非晶質系矽薄膜層13時,可使用SiH4與H2、PH3、B2H6之混合氣體。
採行電漿CVD法時,頻率譬如約為13.56MHz或40.68MHz,且約為40.68MHz較佳,而反應壓力為5Pa以上且小於300Pa,並以50Pa以上且小於200Pa較佳,RF或VHF功率譬如約為1mW/cm2以上且小於500mW/cm2,並以約5mW/cm2以上且小於100mW/cm2較佳。積層各非晶質系矽薄膜時矽基板11之溫度可設為超過180℃且220℃以下(形成溫度)。將形成溫度設為較高之前述溫度範圍,可得到能抑制結晶化且降低缺陷產生之非晶質系薄膜。該控制形成溫度所產生之效果在形成與表面具有微細凹凸之矽基板11直接接合的薄膜(本質非晶質系矽薄膜層(i層)12、非晶質矽薄膜層(i層)14)時尤為顯著。即,可抑制凹凸部之凹溝部分局部產生磊晶膜。
繼之,藉由離子鍍法於上下面形成透明導電氧化物16、17後,藉由網版印刷法形成梳狀之集電極18、19。
於表2敘明錐狀凹凸部A~E之錐體的對角線平均長度L、短路電流密度、開路電壓、填充因數與轉換效率之關係。
關於短路電流密度,對角線平均長度為4μm之(C)與平均長度為3μm之(D)形成密度高的結果。短路電流密度之差起因於源自矽基板表面之反射率低。對角線平均長度為7μm之(A)與平均長度為5μm之(B)中,具有未形成有凹凸部之(100)面殘留在矽基板表面的部位(圖中之實線圓框)與凹凸部過度蝕刻的部位(圖中之虛線圓框)。被認為其等為反射率增加之要因。對角線平均長度為2μm之(E)亦已確認有前述凹凸部過度蝕刻的部位(圖中之虛線圓框)。
關於開路電壓,對角線平均長度為4μm之(C)與平均長度為3μm之(D)形成電壓高的結果。高開路電壓起因於少數載子生命週期高。
對角線平均長度為7μm之(A)與平均長度為5μm之(B)中,具有未形成有凹凸部之(100)面殘留在矽基板表面的部位(圖中之實線圓框),被認為是少數載子生命週期減少之 要因。
關於填充因數之值,對角線平均長度為4μm之(C)與平均長度為3μm之(D)形成數值高的結果。高填充因數之詳細情形不明,推測起因於矽基板表面之表面粗糙度(roughness)。對角線平均長度為7μm之(A)、平均長度為5μm之(B)與平均長度為2μm之(E)中,具有凹凸部過度蝕刻的部位(圖中之虛線圓框),被認為是造成與積層於該等部位之非晶質系矽薄膜間之接合特性惡化、且串聯電阻成分增大的原因。
綜合以上判斷可知,盡可能減低未形成有凹凸部之(100)面殘留在矽基板表面的部位與凹凸部過度蝕刻的部位會關係到性能改善。若將形成錐狀凹凸部之錐體之對角線平均長度L定義為(2×視野範圍之面積/視野範圍之錐體的頂點數)0.5,則對角線之平均長度L須小於5μm,並以2μm以上(甚至3μm以上)且4μm以下為佳。若錐狀凹凸部之對角線尺寸達5μm以上,則未形成有凹凸部的部位或凹凸部過度蝕刻的部位增加,無法發揮光伏電力元件之最大輸出。
又,蝕刻時間越短則產能越高,故蝕刻時間短仍可緻密形成凹凸部之對角線平均長度L宜於2μm以上且5μm以下之範圍。只要對角線平均長度L小於5μm,尤其於2~4μm之範圍時,深度方向之蝕刻量可降低至小於3.5μm(單面),因此亦適合使矽基板之厚度也變薄(例如60~200μm,較佳為70~120μm),可削減矽使用量。加之, 錐體之對角線平均長度L與表面凹凸之深度緊密相關。因此,亦可形成使集電極18、19(指狀電極)厚度變薄(例如1~5μm之厚度)的集電極圖案。經此將指狀電極變薄,亦可減少銀糊等之使用量而可低價提供太陽電池。在形成厚度薄之指狀電極的方法上,宜使用譬如凹版膠印(gravure offset printing)。指狀電極之厚度宜為1μm以上,電極指厚度小於1μm有實施上的困難,且電性組抗更為增加。
本發明人實際實驗專利文獻1記載之技術後得知,不僅會提升填充因數,且可提升開路電壓。依據非專利文獻1所示,凹凸部之凹溝(凹谷)部分局部生成磊晶膜時,表面復合速度快了4倍,成為使開路電壓大幅降低之要因。詳細情形不明,推測是凹凸部之凹溝部分難以引起自由基種之表面擴散,且非專利文獻1記載之局部應力產生作用,再加上凹凸部之凹溝部分局部形成磊晶膜。推測專利文獻1記載之技術係使凹凸部圓滑形成以抑制凹凸部之凹溝部分局部形成磊晶膜,因此不僅會提升填充因數,且可提升開路電壓。
為了在不使用專利文獻1記載之技術下降低局部磊晶膜,發明人認為擴大錐狀凹凸部之尺寸減少凹溝部為有效方法。然而,若擴大錐狀凹凸部之尺寸會產生未形成有凹凸部之(100)面殘留在矽基板表面的部位而導致開路電壓下降。因此,若為減低該(100)面部而延長蝕刻時間,則容易產生凹凸部過度蝕刻的部位,導致填充因數降低。
非專利文獻1顯示,(100)面之表面復合速度較 (111)面快40倍,認為是(100)面之露出就算面積小仍會導致開路電壓顯著降低。另一方面,本實施型態將形成錐狀凹凸部之錐體的對角線平均長度L定義為(2×視野範圍之面積/視野範圍之錐體的頂點數)0.5時,對角線平均長度L係於2μm以上且小於5μm之範圍,無論凹凸部之凹溝部份增多與否,皆可得到720mV以上之高開路電壓。此一結果,亦與藉由化學氣相沉積法於矽基板上形成非晶質系矽薄膜時,係在前述矽基板之溫度超過180℃且在220℃以下之較高溫狀態下進行有關。只要在較高溫下進行則自由基種之表面擴散變活躍,且凹凸部之凹溝部分難以局部形成磊晶膜。藉此,應可享前述(100)面幾乎未露出所帶來的好處,並可得到高開路電壓。另外,前述效果係使用「ALKA-TEX ZERO」而得,但改以林純藥工業股份有限公司製「TAD70」作為添加劑亦可得同樣效果,應對對角線之平均長度而言為普遍可用者。
本發明之要點在於將矽基板之錐形凹凸部的對角線平均長度設於特定範圍,而進行異向性蝕刻之方法及藥劑則非課題,故例如日本專利特開2010-74102號公報記載之「矽基板之蝕刻方法」、特開2009-206335號公報記載之「矽異向性蝕刻液組成物」、特開2012-227304號公報記載之「蝕刻液組成物及蝕刻方法」等技術當然可以運用。
另,本發明之太陽電池模組係具備以上說明之光伏電力元件而構成。太陽電池模組之(太陽電池面板)之基本構造係呈串聯之複數光伏電力元件隔著密封材料挾於 玻璃等表面面板與背板間的構造。亦可運用例如日本專利特表2005-536894號公報記載之「光伏電力電池用電極、光伏電力電池及光伏電力模組」之技術。藉由與業已使指狀電極厚度變薄之(例如1~5μm之厚度)集電極圖案組合,可達減少電阻之效果,並可提供效率更高之太陽電池模組。又,設置必要數目之該太陽電池模組,可構成太陽電池系統。太陽電池模組及太陽電池系統中可適當裝設用以連接之端子及控制電路等控制設備等。
本發明並非以前述實施形態為限,在不變更本發明要旨之範圍內其構成均可變更。舉例言之,本發明中所謂「非晶質系」不僅是非晶體之意,亦包含微晶體,可適時改換。
例如前述實施形態中,可由矽基板之表背面受光而發電,但僅從表側受光時,可使背面之構造更為簡略。
10‧‧‧光伏電力元件
11‧‧‧矽基板
12‧‧‧本質非晶質系矽薄膜層
13‧‧‧p型非晶質系矽薄膜層
14‧‧‧本質非晶質系矽薄膜層
15‧‧‧n型非晶質系矽薄膜層
16、17‧‧‧透明導電氧化物
18、19‧‧‧梳狀集電極(指狀電極)

Claims (2)

  1. 一種光伏電力元件之製造方法,該光伏電力元件係具備經由異向性蝕刻而於表面形成有多數錐狀凹凸部之矽基板,以及藉由化學氣相沉積法而形成於前述錐狀凹凸部上之非晶質系矽薄膜;該製造方法之特徵在於具有:一蝕刻步驟,係對蝕刻前矽基板進行前述異向性蝕刻而獲得前述矽基板,該異向性蝕刻不使用異丙醇,而是使用鹼、含有醇衍生物及界面活性劑中至少1種之添加劑、與水之混合液,其中該醇衍生物是由羧酸、醛或酯所構成;以及一積層步驟,係在前述矽基板之溫度為超過180℃且220℃以下的狀態下,藉由化學氣相沉積法來積層用以與前述矽基板直接接合的非晶質系矽薄膜,且,按下述算式定義,形成前述錐狀凹凸部之錐體的對角線平均長度係3μm以上且小於5μm;對角線之平均長度=(2×視野範圍之面積/視野範圍之錐體的頂點數)0.5
  2. 如請求項1之光伏電力元件之製造方法,其中前述混合液之鹼濃度以NaOH換算計為0.2~2質量%;前述蝕刻步驟係將前述蝕刻前矽基板浸漬於前述混合液中10~20分鐘;且該製造方法在前述蝕刻步驟與前述積層步驟之間更具有一清洗步驟,以進行前述矽基板之清洗處理。
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