氫氣輔助無毒硒化之低缺陷銅銦硒薄膜於太陽能電池應用

Abstract

隨著能源耗竭以及溫室效應的問題越趨嚴重，全世界在各種替代能源的開發和研究上也相當重視。而太陽能因為資源豐富，使用無噪音等優點，因此各種太陽能電池也不斷發展著。銅銦硒薄膜太陽能電池因其高光電轉換效率、高吸光特性、抗輻射能力強、高穩定性的特性，是所有薄膜太陽能電池中最具潛力成為主流產品之一。 本實驗將氫氣加入硒化製程中，氫氣有助於晶粒的長成，隨著氫氣比例提升，晶粒大小也隨之增加，當氫氣比例為20%時晶粒大小約2um。另外氫氣有助於金屬硒蒸氣擴散進入前驅層薄膜，在背電極與銅銦硒薄膜間形成二硒化鉬。因此氫氣輔助硒化製程可提升銅銦硒薄膜太陽能電池的光電轉換效率，還可以改善大面積(30cm*40cm)硒化外觀均勻性的問題。我們利用了掃描式電子顯微鏡的剖面微結構分析來觀察薄膜形貌，以及利用光激發螢光頻譜來驗證薄膜缺陷的降低。另外也一併探討了二硒化鉬在銅銦硒薄膜太陽能電池的影響，在背電極和銅銦硒薄膜間可形成歐姆接觸，降低串聯電阻而提升電池的填充因子。最後成功製作出轉換效率高達9.47%，開路電壓為0.46V，短路電流密度31.39mA/cm2，填充因子65.6%的銅銦硒薄膜太陽能電池。最後更將銅銦硒薄膜依現有的微影蝕刻技術，成功轉移60um*60um的圖案輪廓，對於未來不論在太陽能電池或薄膜電晶體的應用上，都展現極高的潛力。

As the increasing crisis of energy depletion and greenhouse effect, the development and research of alternative energy becomes more and more important around the whole world. Photovoltaics processes the advantages of abundant resources, noise-free…etc, so it has become a thriving industry. Copper-indium-diselenide(CIS) thin film solar cells show high conversion efficiency, high absorption properties, high radiation resistance and high stability, which make it be one of the most potential products beyond all thin film solar cells. In this study, we apply hydrogen to the selenization process, the CIS grain size increases with the increasing hydrogen content ratio. As the hydrogen content ratio reaches 20%, grain size is about 2um. In addition, hydrogen also enhances the diffusion behavior of metal Se vapors into the precursor film and formed MoSe2 between the back electrode and CIS thin film. So hydrogen is helpful to enhance the conversion efficiency of CIS thin film solar cells and improve the large area (30cm*40cm) uniformity. We observe the CIS thin film morphology by SEM cross-section inspection, and verify the reduction of CIS thin film defects via PL intensity analysis. MoSe2 formation thickness effect in CIS thin film solar cells is also discussed, MoSe2 form an ohmic contact between the Mo and CIS thin film and play an important role of reducing the series resistance and further enhance the fill factor. Finally, we have successfully produced high efficiency CIS thin film solar cells up to 9.47%, and exhibit Voc of 0.46 V, Jsc of 31.39mA/cm2 and fill factor of 65.6%. Besides, we also integrate the existing lithography technology and pattern CIS thin film within 60um*60um pixel size, which show the great potential to future thin film transistor applications.