Nanobowl optical concentrator for efficient light trapping and high-performance organic photovoltaics

Geometrical light trapping is a simple and promising strategy to largely improve the optical absorption and efficiency of solar cell. Nonetheless, implementation of geometrical light trapping in organic photovoltaic is challenging due to the fact that uniform organic active layer can rarely be achieved on textured substrate. In this work, squarely ordered nanobowl array (SONA) is reported for the first time and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM):poly(3-hexylthiophene) (P3HT)-based organic photovoltaic (OPV) device on SONA demonstrated over 28% enhancement in power conversion efficiency over the planar counterpart. Interestingly, finite-difference time-domain (FDTD) optical simulation revealed that the superior light trapping by SONA originated from optical concentrator effect by nanobowl. Furthermore, aiming at low-cost, solution processible, and resource sustainable flexible solar cells, we employed Ag nanowires for the top transparent conducting electrode. This work not only revealed the in-depth understanding of light trapping by nanobowl optical concentrator, but also demonstrated the feasibility of implementing geometrical light trapping in OPV.