New Deposition Technique for Inverted Polymer Solar Cells Using ZnO-ETL

Abstract

In this research work, efficient inverted polymer solar cells (iPSCs) were fabricated for the first time using simple and low cost spray pyrolysis (SP) technique to deposit ZnO thin film as electron transporting layer (ETL) with the structure of ITO/ZnO/PTB7-Th: PC 70 BM/V 2 O 5 /Ag. The effect of the different number of running cycles with the SP technique on the iPSC performance has been investigated. In addition, a state of the art for iPSCs fabricated by spin coating technique has been used as reference. In the spray pyrolysis technique, ZnO thin films were fabricated by spraying the ZnO precursor solution onto the preheated ITO substrate. Two different numbers of running cycles of ZnO were performed, namely, 15R and 20R. By increasing the running cycles of the sprayed ZnO f ilm, the fill factor and the power conversion efficiency were enhanced by 20% and 32 %, respectively. This improvement might be attributed to enhancing the roughness with compacted film formation and the matched band gap between the active layer (PTB7-Th: PC 70 BM) and the ZnO-ETL. Hence, this promising spray pyrolysis technique might facilitate the commercialization of polymer solar cells based on mass production besides the possibility of improving its efficiency.