Advancements in Top electrode materials for semi-transparent organic solar cells

A significant research effort has been pushed to develop semi-transparent solar cells in last one decade. Organic solar cells (OSCs)’s band gap tunability in near-infrared, and thin film depositions characteristic appeal them attractive as a semi-transparent solar cell. It’s application in wearable energy generation, building-integrated solar cells, agrivoltaics, and the automotive industries, etc. become focus of interest. In OSCs device structure, apart from photoactive layer the top electrode materials play an essential role to maintain the device transparency and the performance. Thus, the choice of the top electrode material is crucial. A few materials such as thin metal film and nanowires, Metal/dielectric/Metal structures, PEDOT: PSS, graphene, and CNT have been reported so far. To date, the highest power conversion efficiency (PCE) reported for OSCs up to 16% with 25.2 % average visible transmittance (AVT %) by using a metal: polymer film as the transparent top electrode (TTE). However, there is an enhancement needed to maintain high transparency with improved device performance. In this review, we discussed atop electrode properties required for transparent or semi-transparent organic solar cells (ST-OSCs). We have also discussed the materials stability, scalability, current challenges, and future perspectives of top electrode materials for ST-OSCs. Also, summarized the top electrode materials reported so far.