高效率之銅鋅錫硒太陽能電池研究

Investigation of High Quality Cu2ZnSnSe4(CZTSe) Solar Cells

本文介紹蒸鍍－後硒化法製備高品質銅鋅錫硒-Cu2ZnSnSe4（CZTSe）薄膜，我們藉由改變不同硒化溫度來探討其對CZTSe薄膜的光電特性影響。從X光繞射（XRD）結果得知成長薄膜皆呈現（112）的優選取向，拉曼光譜（Raman spectroscopy）量測亦呈現CZTSe材料的單一特徵訊號。後續利用掃描式電子顯微鏡（SEM）及能量散射X射線光譜儀（EDS）進行分析，可以明顯看出硒化溫度對薄膜微結構以及錫硒原子損耗程度的影響。光激螢光光譜（PL）的量測數據顯示薄膜能隙也受到原子比例變化影響，能隙值呈現0.88－0.93 eV的改變。整體而言，在硒化溫度500°C下成長的CZTSe薄膜製作的太陽能電池擁有最佳光電轉換效率7.18%。 Polycrystalline Cu2ZnSnSe4(CZTSe) thin films were fabricated by evaporation and following selenization. Singlephase CZTSe fi lms were formed in the temperature range of 480–540 °C, with a selenization step of 30 min. X-ray diffraction and Raman spectroscopy revealed that these thin films exhibited high crystallinity and strong preferential orientation along the(112) direction, confi rming the presence of the kesterite CZTSe phase. The films prepared at temperatures above 520 °C showed many voids at the bottom of the CZTSe absorber layer. This phenomenon is attributed to Sn loss during high-temperature growth and is confi rmed by scanning electron microscopy and energy dispersive X-ray spectroscopy analyses. The band gaps(Eg) of the CZTSe thin films varied from 0.88 to 0.93 eV, depending on the SnSex loss during selenization. The solar cell fabricated with the CZTSe film grown at 500 °C showed the best conversion efficiency of 7.18%, with open-circuit voltage of 0.38 V, short-circuit current density of 42.34 mA/cm2, and fi ll factor of 44%.