Colorful Transparent Silicon Photovoltaics with Unprecedented Flexibility

Abstract

Integrated photovoltaics are regarded as next-generation photovoltaic technologies that can generate electricity in urban areas with limited available land while also serving as aesthetic architectural elements. The criteria for integrating photovoltaics into buildings and electronic devices are flexibility, color tunability, efficiency, scalability, and stability. It is very challenging for integrated photovoltaics to demonstrate all-around performance benefits because photovoltaic performances exist in a trade-off relation, such as that between transparency and efficiency. Here, great all-around transparent solar cells (TSC) featuring high flexibility and high transparency with color-tunable solar cells are demonstrated. The TSCs exhibit an efficiency of 7.38% and 5.52% at the average visible transparencies of 45% and 60%, respectively. Moreover, by introducing a periodic hole array structure, the flexibility of TSCs is dramatically improved. The minimum bending radius decreases to 6 mm; it further decreases to 3 mm after PDMS embedding. The results of the numerical simulation show that the periodic hole array structure uniformly distributes the stress across the entire area as a self-stress relief structure. The PDMS-embedded TSCs demonstrate unprecedently high flexibility and long-term stability without significant degradation even after cyclic bending deformations up to 1000 cycles and 1500 h of the standard damp heat test.