薄膜太陽能電池原理

在(zai)化(hua)(hua)(hua)學(xue)電(dian)(dian)池中(zhong)(zhong)，化(hua)(hua)(hua)學(xue)能直接轉變為(wei)電(dian)(dian)能是靠(kao)電(dian)(dian)池內(nei)部自發進行(xing)氧(yang)(yang)化(hua)(hua)(hua)、還原等(deng)(deng)化(hua)(hua)(hua)學(xue)反(fan)應的結(jie)果，這種(zhong)反(fan)應分(fen)別在(zai)兩個電(dian)(dian)極(ji)上進行(xing)。負極(ji)活性(xing)物(wu)(wu)(wu)質由電(dian)(dian)位較負并在(zai)電(dian)(dian)解質中(zhong)(zhong)穩定(ding)的還原劑(ji)組(zu)(zu)成，如鋅、鎘、鉛等(deng)(deng)活潑金屬和(he)氫或(huo)碳氫化(hua)(hua)(hua)合物(wu)(wu)(wu)等(deng)(deng)。正極(ji)活性(xing)物(wu)(wu)(wu)質由電(dian)(dian)位較正并在(zai)電(dian)(dian)解質中(zhong)(zhong)穩定(ding)的氧(yang)(yang)化(hua)(hua)(hua)劑(ji)組(zu)(zu)成，如二氧(yang)(yang)化(hua)(hua)(hua)錳、二氧(yang)(yang)化(hua)(hua)(hua)鉛、氧(yang)(yang)化(hua)(hua)(hua)鎳等(deng)(deng)金屬氧(yang)(yang)化(hua)(hua)(hua)物(wu)(wu)(wu)，氧(yang)(yang)或(huo)空(kong)氣(qi)，鹵素及(ji)(ji)其鹽類，含氧(yang)(yang)酸及(ji)(ji)其鹽類等(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)，但沒有電(dian)(dian)(dian)流，存儲(chu)在(zai)電(dian)(dian)(dian)池中的(de)化(hua)學能并不(bu)轉(zhuan)換為電(dian)(dian)(dian)能。當外電(dian)(dian)(dian)路閉合(he)時，在(zai)兩電(dian)(dian)(dian)極電(dian)(dian)(dian)位差的(de)作用下即有電(dian)(dian)(dian)流流過(guo)外電(dian)(dian)(dian)路。

同時在電池內部(bu)，由于電解質(zhi)中(zhong)不存在自由電子，電荷的傳遞必然(ran)伴(ban)隨(sui)兩極活性物質(zhi)與(yu)電解質(zhi)界面的氧(yang)化(hua)或(huo)還原反(fan)應(ying)，以及反(fan)應(ying)物和反(fan)應(ying)產物的物質(zhi)遷移。電(dian)荷(he)在電(dian)解質(zhi)中的(de)傳(chuan)遞(di)也(ye)要(yao)由離子的(de)遷移(yi)來(lai)完成(cheng)。因此，電(dian)池(chi)內(nei)部正常的(de)電(dian)荷(he)傳(chuan)遞(di)和(he)物(wu)質(zhi)傳(chuan)遞(di)過程(cheng)是保(bao)證(zheng)正常輸出(chu)電(dian)能的(de)必要(yao)條(tiao)件。充電(dian)時，電(dian)池(chi)內(nei)部的(de)傳(chuan)電(dian)和(he)傳(chuan)質(zhi)過程(cheng)的(de)方向恰與放電(dian)相反；電(dian)極反應必須是可逆的(de)，才能保(bao)證(zheng)反方向傳(chuan)質(zhi)與傳(chuan)電(dian)過程(cheng)的(de)正常進行。

因此，電(dian)極反應(ying)可逆是構成蓄電(dian)池的必要條件。為吉(ji)布(bu)斯(si)反應(ying)自由能增量(焦)；F為法拉第常數=96500庫=26.8安·小時；n為電(dian)(dian)(dian)池反應的(de)(de)當量(liang)數(shu)。這是(shi)(shi)電(dian)(dian)(dian)池電(dian)(dian)(dian)動(dong)勢(shi)與電(dian)(dian)(dian)池反應之間的(de)(de)基本熱力學(xue)(xue)關(guan)系式(shi)，也是(shi)(shi)計算(suan)電(dian)(dian)(dian)池能(neng)量(liang)轉換(huan)效率的(de)(de)基本熱力學(xue)(xue)方程(cheng)式(shi)。實(shi)際(ji)上，當電(dian)(dian)(dian)流(liu)(liu)流(liu)(liu)過電(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(yao)偏離熱力學(xue)(xue)平衡的(de)(de)電(dian)(dian)(dian)極(ji)(ji)(ji)(ji)(ji)(ji)電(dian)(dian)(dian)勢(shi)，這種(zhong)現象稱(cheng)為極(ji)(ji)(ji)(ji)(ji)(ji)化(hua)(hua)(hua)(hua)。電(dian)(dian)(dian)流(liu)(liu)密度(du)（單(dan)位電(dian)(dian)(dian)極(ji)(ji)(ji)(ji)(ji)(ji)面(mian)積上通(tong)過的(de)(de)電(dian)(dian)(dian)流(liu)(liu)）越大，極(ji)(ji)(ji)(ji)(ji)(ji)化(hua)(hua)(hua)(hua)越嚴重。極(ji)(ji)(ji)(ji)(ji)(ji)化(hua)(hua)(hua)(hua)現象是(shi)(shi)造(zao)(zao)成(cheng)電(dian)(dian)(dian)池能(neng)量(liang)損失的(de)(de)重要(yao)原因之一(yi)。極(ji)(ji)(ji)(ji)(ji)(ji)化(hua)(hua)(hua)(hua)的(de)(de)原因有三：①由電(dian)(dian)(dian)池中(zhong)各部分電(dian)(dian)(dian)阻造(zao)(zao)成(cheng)的(de)(de)極(ji)(ji)(ji)(ji)(ji)(ji)化(hua)(hua)(hua)(hua)稱(cheng)為歐姆極(ji)(ji)(ji)(ji)(ji)(ji)化(hua)(hua)(hua)(hua)；②由電(dian)(dian)(dian)極(ji)(ji)(ji)(ji)(ji)(ji)－電(dian)(dian)(dian)解質(zhi)界面(mian)層(ceng)中(zhong)電(dian)(dian)(dian)荷傳(chuan)(chuan)遞過程(cheng)的(de)(de)阻滯造(zao)(zao)成(cheng)的(de)(de)極(ji)(ji)(ji)(ji)(ji)(ji)化(hua)(hua)(hua)(hua)稱(cheng)為活(huo)化(hua)(hua)(hua)(hua)極(ji)(ji)(ji)(ji)(ji)(ji)化(hua)(hua)(hua)(hua)；③由電(dian)(dian)(dian)極(ji)(ji)(ji)(ji)(ji)(ji)－電(dian)(dian)(dian)解質(zhi)界面(mian)層(ceng)中(zhong)傳(chuan)(chuan)質(zhi)過程(cheng)遲緩而造(zao)(zao)成(cheng)的(de)(de)極(ji)(ji)(ji)(ji)(ji)(ji)化(hua)(hua)(hua)(hua)稱(cheng)為濃差極(ji)(ji)(ji)(ji)(ji)(ji)化(hua)(hua)(hua)(hua)。減(jian)(jian)小極(ji)(ji)(ji)(ji)(ji)(ji)化(hua)(hua)(hua)(hua)的(de)(de)方法是(shi)(shi)增大電(dian)(dian)(dian)極(ji)(ji)(ji)(ji)(ji)(ji)反應面(mian)積、減(jian)(jian)小電(dian)(dian)(dian)流(liu)(liu)密度(du)、提(ti)高反應溫度(du)以及改善電(dian)(dian)(dian)極(ji)(ji)(ji)(ji)(ji)(ji)表面(mian)的(de)(de)催化(hua)(hua)(hua)(hua)活(huo)性。

該圖片由注冊用戶"妮子的文字"提供，版權聲明反饋

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著明顯的減少，制(zhi)造程序上所需(xu)(xu)的能(neng)量也較堆積型太(tai)陽(yang)能(neng)電池來(lai)的小，它同時也擁有整合型式的連接模塊(kuai)，如此(ci)一來(lai)便可省下了獨立模塊(kuai)所需(xu)(xu)在(zai)固定和(he)內部(bu)連接的成本。

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，因為材料的不同而使非晶硅太陽能電池(chi)(chi)的構造與晶硅太陽能電池(chi)(chi)稍(shao)有不同。

SiH4最大(da)的優點為吸光效果(guo)及光導效果(guo)都很好(hao)，但(dan)其(qi)電氣(qi)特(te)性類似絕(jue)緣體，與硅的半導體特(te)性相差甚遠(yuan)，因此最初(chu)認為SiH4是不(bu)適合的材料(liao)。但(dan)在1970年代科學家克服了這個問(wen)題，不久后(hou)美國的RCA制(zhi)造(zao)出(chu)第(di)一個非(fei)晶硅太陽能電池。雖然SiH4吸光效果及(ji)光導效果都很好(hao)，但由于(yu)其結晶(jing)構(gou)造(zao)比多(duo)晶(jing)硅太陽能電池差，所以懸浮(fu)鍵的問題比多(duo)晶(jing)硅太陽能電池還(huan)嚴重，自由電子與電洞復合的速率非常快；此外SiH4的結晶構造不規則會阻礙電子與(yu)電洞的移動使(shi)得擴散范圍變短。

基于以(yi)上(shang)兩個因(yin)素(su)，因(yin)此當光照射在SiH4上產生(sheng)電(dian)子(zi)(zi)(zi)電(dian)洞(dong)(dong)(dong)對(dui)后，必須盡快將電(dian)子(zi)(zi)(zi)與電(dian)洞(dong)(dong)(dong)分離，才能有效產生(sheng)光電(dian)效應。所以(yi)非晶硅太陽能電(dian)池大多做得很薄，以(yi)減少自由電(dian)子(zi)(zi)(zi)與電(dian)洞(dong)(dong)(dong)復合(he)。由于SiH4的吸光效果很好，雖(sui)然(ran)非晶硅太陽(yang)能電(dian)池(chi)做得很薄，仍然(ran)可以吸收(shou)大部分的光。

非(fei)(fei)晶硅太陽能(neng)(neng)電(dian)池最大的(de)優點為成本低，而缺點則是效率低及光電(dian)轉換(huan)效率隨使(shi)用時間衰退的(de)問題。因此非(fei)(fei)晶硅太陽能(neng)(neng)電(dian)池在(zai)小電(dian)力市場(chang)上被廣泛使(shi)用，但在(zai)發電(dian)市場(chang)上則較(jiao)不具競爭力。