薄膜太陽能電池原理

在(zai)(zai)(zai)化(hua)(hua)學(xue)電(dian)(dian)(dian)池中(zhong)，化(hua)(hua)學(xue)能直接轉(zhuan)變為電(dian)(dian)(dian)能是靠電(dian)(dian)(dian)池內部(bu)自(zi)發(fa)進行氧(yang)(yang)(yang)(yang)化(hua)(hua)、還(huan)原等(deng)(deng)(deng)化(hua)(hua)學(xue)反(fan)應(ying)的結果，這種反(fan)應(ying)分(fen)別在(zai)(zai)(zai)兩個電(dian)(dian)(dian)極上(shang)進行。負極活性(xing)物質(zhi)由電(dian)(dian)(dian)位(wei)(wei)較(jiao)(jiao)負并在(zai)(zai)(zai)電(dian)(dian)(dian)解(jie)質(zhi)中(zhong)穩定(ding)的還(huan)原劑(ji)組(zu)成，如(ru)鋅、鎘、鉛等(deng)(deng)(deng)活潑金屬和氫(qing)或(huo)(huo)碳(tan)氫(qing)化(hua)(hua)合物等(deng)(deng)(deng)。正極活性(xing)物質(zhi)由電(dian)(dian)(dian)位(wei)(wei)較(jiao)(jiao)正并在(zai)(zai)(zai)電(dian)(dian)(dian)解(jie)質(zhi)中(zhong)穩定(ding)的氧(yang)(yang)(yang)(yang)化(hua)(hua)劑(ji)組(zu)成，如(ru)二(er)氧(yang)(yang)(yang)(yang)化(hua)(hua)錳、二(er)氧(yang)(yang)(yang)(yang)化(hua)(hua)鉛、氧(yang)(yang)(yang)(yang)化(hua)(hua)鎳等(deng)(deng)(deng)金屬氧(yang)(yang)(yang)(yang)化(hua)(hua)物，氧(yang)(yang)(yang)(yang)或(huo)(huo)空(kong)氣，鹵素及其鹽(yan)(yan)類(lei)，含(han)氧(yang)(yang)(yang)(yang)酸及其鹽(yan)(yan)類(lei)等(deng)(deng)(deng)。

電解質則是具有良好離子導電性的材料，如酸、堿、鹽的水溶液，有機或無機非水溶液、熔融鹽或固體電解質等。當外電路斷開時，兩極之間雖然有電位差(開路電壓)，但沒(mei)有電(dian)流(liu)，存(cun)儲在(zai)電(dian)池中的化學能(neng)并不轉換(huan)為電(dian)能(neng)。當外電(dian)路(lu)閉(bi)合時(shi)，在(zai)兩電(dian)極電(dian)位差的作用下即有電(dian)流(liu)流(liu)過(guo)外電(dian)路(lu)。

同時在電(dian)池內部，由于電(dian)解(jie)質(zhi)中(zhong)不存在自由電(dian)子，電(dian)荷(he)的(de)傳遞必然伴(ban)隨(sui)兩極活性物(wu)質(zhi)與電(dian)解(jie)質(zhi)界面的(de)氧(yang)化或還原反(fan)應(ying)，以及反(fan)應(ying)物(wu)和反(fan)應(ying)產物(wu)的(de)物(wu)質(zhi)遷移。電(dian)(dian)荷在電(dian)(dian)解質(zhi)(zhi)中的(de)(de)(de)傳遞(di)也要(yao)由離(li)子的(de)(de)(de)遷(qian)移來完(wan)成。因此，電(dian)(dian)池內部正(zheng)(zheng)常的(de)(de)(de)電(dian)(dian)荷傳遞(di)和(he)物質(zhi)(zhi)傳遞(di)過(guo)(guo)程(cheng)是(shi)保(bao)證正(zheng)(zheng)常輸出(chu)電(dian)(dian)能(neng)的(de)(de)(de)必要(yao)條件(jian)。充電(dian)(dian)時，電(dian)(dian)池內部的(de)(de)(de)傳電(dian)(dian)和(he)傳質(zhi)(zhi)過(guo)(guo)程(cheng)的(de)(de)(de)方(fang)向(xiang)恰與放電(dian)(dian)相反(fan)；電(dian)(dian)極反(fan)應必須(xu)是(shi)可逆的(de)(de)(de)，才(cai)能(neng)保(bao)證反(fan)方(fang)向(xiang)傳質(zhi)(zhi)與傳電(dian)(dian)過(guo)(guo)程(cheng)的(de)(de)(de)正(zheng)(zheng)常進(jin)行(xing)。

因此，電(dian)極反(fan)應可(ke)逆是構成蓄電(dian)池的必(bi)要(yao)條件。為吉布斯反(fan)應自由能增量(焦)；F為法拉第常數(shu)=96500庫=26.8安(an)·小時(shi)；n為(wei)電(dian)(dian)(dian)池(chi)反(fan)應(ying)(ying)的(de)(de)(de)當量數。這是(shi)電(dian)(dian)(dian)池(chi)電(dian)(dian)(dian)動勢(shi)與電(dian)(dian)(dian)池(chi)反(fan)應(ying)(ying)之間(jian)的(de)(de)(de)基本(ben)熱力(li)(li)學關系式(shi)，也是(shi)計算電(dian)(dian)(dian)池(chi)能量轉換效率(lv)的(de)(de)(de)基本(ben)熱力(li)(li)學方(fang)程(cheng)式(shi)。實際上，當電(dian)(dian)(dian)流(liu)(liu)(liu)流(liu)(liu)(liu)過(guo)電(dian)(dian)(dian)極(ji)(ji)(ji)(ji)(ji)(ji)時(shi)，電(dian)(dian)(dian)極(ji)(ji)(ji)(ji)(ji)(ji)電(dian)(dian)(dian)勢(shi)都要偏離熱力(li)(li)學平(ping)衡的(de)(de)(de)電(dian)(dian)(dian)極(ji)(ji)(ji)(ji)(ji)(ji)電(dian)(dian)(dian)勢(shi)，這種現象稱為(wei)極(ji)(ji)(ji)(ji)(ji)(ji)化(hua)(hua)(hua)。電(dian)(dian)(dian)流(liu)(liu)(liu)密度（單位電(dian)(dian)(dian)極(ji)(ji)(ji)(ji)(ji)(ji)面(mian)積(ji)上通過(guo)的(de)(de)(de)電(dian)(dian)(dian)流(liu)(liu)(liu)）越大，極(ji)(ji)(ji)(ji)(ji)(ji)化(hua)(hua)(hua)越嚴重。極(ji)(ji)(ji)(ji)(ji)(ji)化(hua)(hua)(hua)現象是(shi)造(zao)成電(dian)(dian)(dian)池(chi)能量損失的(de)(de)(de)重要原因之一。極(ji)(ji)(ji)(ji)(ji)(ji)化(hua)(hua)(hua)的(de)(de)(de)原因有三：①由(you)電(dian)(dian)(dian)池(chi)中各部分(fen)電(dian)(dian)(dian)阻造(zao)成的(de)(de)(de)極(ji)(ji)(ji)(ji)(ji)(ji)化(hua)(hua)(hua)稱為(wei)歐姆極(ji)(ji)(ji)(ji)(ji)(ji)化(hua)(hua)(hua)；②由(you)電(dian)(dian)(dian)極(ji)(ji)(ji)(ji)(ji)(ji)－電(dian)(dian)(dian)解質界面(mian)層中電(dian)(dian)(dian)荷傳遞過(guo)程(cheng)的(de)(de)(de)阻滯造(zao)成的(de)(de)(de)極(ji)(ji)(ji)(ji)(ji)(ji)化(hua)(hua)(hua)稱為(wei)活化(hua)(hua)(hua)極(ji)(ji)(ji)(ji)(ji)(ji)化(hua)(hua)(hua)；③由(you)電(dian)(dian)(dian)極(ji)(ji)(ji)(ji)(ji)(ji)－電(dian)(dian)(dian)解質界面(mian)層中傳質過(guo)程(cheng)遲緩而造(zao)成的(de)(de)(de)極(ji)(ji)(ji)(ji)(ji)(ji)化(hua)(hua)(hua)稱為(wei)濃差極(ji)(ji)(ji)(ji)(ji)(ji)化(hua)(hua)(hua)。減(jian)小極(ji)(ji)(ji)(ji)(ji)(ji)化(hua)(hua)(hua)的(de)(de)(de)方(fang)法是(shi)增大電(dian)(dian)(dian)極(ji)(ji)(ji)(ji)(ji)(ji)反(fan)應(ying)(ying)面(mian)積(ji)、減(jian)小電(dian)(dian)(dian)流(liu)(liu)(liu)密度、提高反(fan)應(ying)(ying)溫度以及改善(shan)電(dian)(dian)(dian)極(ji)(ji)(ji)(ji)(ji)(ji)表面(mian)的(de)(de)(de)催(cui)化(hua)(hua)(hua)活性。

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薄膜太陽能電池優缺點

薄膜型太陽能電池由于使用材料較少，就每一模塊的成本而言比起堆積型太陽能電池有(you)著(zhu)明顯的(de)減少，制造程序上所(suo)需(xu)的(de)能(neng)量也較堆積型太陽能(neng)電池來(lai)的(de)小，它(ta)同時也擁(yong)有(you)整合型式(shi)的(de)連接模(mo)塊(kuai)，如此(ci)一來(lai)便(bian)可省下了獨立模(mo)塊(kuai)所(suo)需(xu)在固(gu)定和內部(bu)連接的(de)成本。

未來薄膜型太陽能電池將可能會取代現今一般常用硅太陽能電池，而成為市場主流。非晶硅太陽能電池與單晶硅太陽能電池或多晶硅太陽能電池的最主要差異是材料的不同，單晶硅太陽能電池或多晶硅太陽能電池的材料都疏，而非晶硅太陽能電池的材料則是SiH4，因為材(cai)料的不同而使非晶硅(gui)(gui)太陽能電池的構造與(yu)晶硅(gui)(gui)太陽能電池稍(shao)有不同。

SiH4最大的優點為(wei)吸光效果及光導效果都很好，但其(qi)電氣(qi)特性類似絕緣體(ti)，與硅的半(ban)導體(ti)特性相(xiang)差甚(shen)遠(yuan)，因(yin)此最初(chu)認為(wei)SiH4是不適合的材(cai)料。但在(zai)1970年代科學家克(ke)服了這個問題，不(bu)久后美(mei)國的RCA制造出第(di)一個非晶硅(gui)太陽(yang)能電池。雖然SiH4吸光(guang)效(xiao)(xiao)果及光(guang)導效(xiao)(xiao)果都很(hen)好，但由于其(qi)結晶構造比(bi)多晶硅(gui)太陽(yang)能電(dian)池(chi)差，所以懸浮鍵的(de)問(wen)題比(bi)多晶硅(gui)太陽(yang)能電(dian)池(chi)還嚴(yan)重(zhong)，自由電(dian)子與(yu)電(dian)洞(dong)復(fu)合(he)的(de)速(su)率(lv)非常快；此外SiH4的結(jie)晶構造不規則會阻礙電子與(yu)電洞的移動使得(de)擴散范(fan)圍(wei)變短。

基于以上兩個因素，因此當(dang)光照射在SiH4上產生電(dian)(dian)(dian)子電(dian)(dian)(dian)洞對后，必須盡(jin)快將(jiang)電(dian)(dian)(dian)子與電(dian)(dian)(dian)洞分(fen)離，才能有(you)效(xiao)產生光電(dian)(dian)(dian)效(xiao)應。所以非晶硅太陽能電(dian)(dian)(dian)池大(da)多做得(de)很薄(bo)，以減少(shao)自由(you)電(dian)(dian)(dian)子與電(dian)(dian)(dian)洞復合。由(you)于SiH4的吸光效(xiao)果(guo)很好，雖然非晶硅太陽能(neng)電(dian)池做得很薄，仍然可以吸收大部(bu)分的光。

非(fei)(fei)晶硅(gui)太陽(yang)(yang)能電(dian)池(chi)最大的優點為(wei)成(cheng)本低，而缺點則(ze)是效(xiao)率(lv)(lv)低及光電(dian)轉換效(xiao)率(lv)(lv)隨使用時(shi)間衰退(tui)的問題。因此非(fei)(fei)晶硅(gui)太陽(yang)(yang)能電(dian)池(chi)在小電(dian)力市場(chang)上(shang)被廣(guang)泛使用，但在發(fa)電(dian)市場(chang)上(shang)則(ze)較(jiao)不具競爭力。