銀銅銦鎵硒太陽電池於可撓式基板之合成與特性分析

Abstract

本研究藉由非真空的旋轉塗佈法將銀銅銦鎵硒(ACIGS)薄膜製備於可繞式不鏽鋼基板上。第一部分為研究不同銀離子含量對銀銅銦鎵硒薄膜與太陽電池之影響。單相黃銅礦結構的(ACIGS)薄膜被成功製備。當銀離子對IB族離子(銀與銅離子)的莫耳比增加至0.2時，轉換效率提升至6.29%。轉換效率的提升是由於液相的(Ag,Cu)2In被觀察到。具有低熔點的中間相(Ag,Cu)2In藉由液相燒結幫助晶粒成長與緻密。薄膜品質的改善有效提升銀銅銦鎵硒太陽電池的光電特性。然而，添加過量的銀離子使薄膜孔洞增加並降低銀銅銦鎵硒太陽電池的轉換效率。 本研究第二部分探討製備於可繞式不鏽鋼基板的銅銦鎵硒與銀銅銦鎵硒薄膜於不同溫度之影響。當溫度上升至550oC時，CIGS與ACIGS的Voc, Jsc. FF與轉換效率皆被提升。而當溫度超過550oC時，CIGS薄膜變成角狀。同時，藉由EDS與SIMS分析發現鐵離子從不鏽鋼基板擴散至吸收層。存在於吸收層內的鐵離子會使CIGS太陽電池短路，導致轉換效率降至零。另一方面，添加銀離子生成ACIGS太陽電池可以增強薄膜在高溫下的穩定性，並抑制鐵離子與吸收層之間的交互作用。

(Ag,Cu)(In,Ga)Se2 thin films were fabricated on flexible stainless steel substrates via the non-vacuum spin-coating process in this thesis. In Chapter 2, the monophasic chalcopyrite-structured (Ag,Cu)(In,Ga)Se2 thin films were formed after selenization at 550oC for 30 min. The conversion efficiency of the (Ag,Cu)(In,Ga)Se2 solar cells was significantly increased to 6.29% when the molar ratio of silver ions to IB ions (silver and copper ions) was increased to 0.2. The increase in conversion efficiency was attributed to the liquid phase formed from (Ag,Cu)2In intermediate compound. The formed liquid phase facilitated the grain growth and promoted the densification of the thin films. The densified thin films of (Ag,Cu)(In,Ga)Se2 suppressed the additional shunt path. When the excessive silver ions were doped in the CIGS thin films, the microstructures of the prepared thin films became porous, and the conversion efficiency of solar cells was reduced. In Chapter 3, Cu(In,Ga)Se2 and (Ag,Cu)(In,Ga)Se2 films were successfully fabricated on stainless steel substrates. As the selenizatoin temperature was increased to 550oC, the Voc, Jsc, FF, and conversion efficiency of both solar cells were enhanced. On selenization at temperature above 550oC, the morphology of Cu(In,Ga)Se2 films become angular shape, and porous microstructures were formed. The analysis of EDS and SIMS revealed that the iron ions were substantially diffused from stainless steel substrates into Cu(In,Ga)Se2 absorber layers. The existence of iron ions in CIGS thin films resulted in formation of the short circuits of CIGS solar cells, thereby dropping the conversion efficiency of solar cells to zero. On the other hand, adding the silver ions into absorber layers effectively enhanced the stability of ACIGS thin films at high selenization process, and suppressed the interaction between the absorber layers and iron ions.