Optimization and development of ITO-free plasmonic gold nanoparticles assisted inverted organic solar cells

We report an indium tin oxide (ITO) free inverted organic solar cell with an alternate aluminium doped zinc oxide (AZO) front cathode layer based on the consideration of blocking harmful ultraviolet (UV) rays, which is one of the prominent reasons for degradation of organic solar cells. To further enhance the power conversion efficiency of AZO/ZnO/PTB7:PC71BM/MoO3/Ag organic solar cell, plasmonic gold nanoflowers were embedded inside the active layer. The critical parameter of thickness of electron transport layer (ETL), hole transport layer (HTL) and active layer war first optimized through simulations using general purpose photovoltaic device model (GPVDM) software. The experimental fabrication of the desired geometry was then carried out based on opti-mized thickness. The power conversion efficiency (PCE) under UV exposure was found remarkably constant for AZO front electrode solar cell was as compared to conventional ITO based organic solar cells. This is attributed to the UV blocking property of AZO. The PCE was boosted from 6.19% to 7.01% on further use of plasmonic Au nanoparticles in the active layer of AZO/ZnO/PTB7:PC71BM/MoO3/Ag. This work provides a practical insight of developing an ITO free, plasmonic nanoparticles assisted inverted organic solar cell with enhanced efficiency and stability.