Current advancements on charge selective contact interfacial layers and electrodes in flexible hybrid perovskite photovoltaics

Perovskite-based photovoltaic materials have been attracting attention for their strikingly improved performance at converting sunlight into electricity. The beneficial and unique optoelectronic characteristics of perovskite structures enable researchers to achieve an incredibly remarkable power conversion efficiency. Flexible hybrid perovskite photovoltaics promise emerging applications in a myriad of optoelectronic and wearable/portable device applications owing to their inherent intriguing physicochemical and photophysical properties which enabled researchers to take forward advanced research in this growing field. Flexible perovskite photovoltaics have attracted significant attention owing to their fascinating material properties with combined merits of high efficiency, light-weight, flexibility, semi-transparency, compatibility towards roll-to-roll printing, and large-area mass-scale production. Flexible perovskite-based solar cells comprise of 4 key components that include a flexible substrate, semi-transparent bottom contact electrode, perovskite (light absorber layer) and charge transport (electron/hole) layers and top (usually metal) electrode. Among these components, interfacial layers and contact electrodes play a pivotal role in influencing the overall photovoltaic performance. In this comprehensive review article, we focus on the current developments and latest progress achieved in perovskite photovoltaics concerning the charge selective transport layers/electrodes toward the fabrication of highly stable, efficient flexible devices. As a concluding remark, we briefly summarize the highlights of the review article and make recommendations for future outlook and investigation with perspectives on the perovskite-based optoelectronic functional devices that can be potentially utilized in smart wearable and portable devices.