Omnidirectional Optical Engineering and Ternary Strategy for High-Performance Indoor Organic Photovoltaics

Indoor organic photovoltaics (IOPVs) with tunable absorption spectra and relatively high power conversion efficiency (PCE) have emerged as one of the most promising energy sources for Internet of Things devices, but enhancing the device performance under various directions of indoor illumination is challenging. Herein, it is proposed to combine omnidirectional optical engineering and ternary strategy for achieving high-performance IOPVs. The advantage is taken of a ternary bulk heterojunction (BHJ) with a polymer donor having aligned absorption spectra with the light-emitting diode (LED) spectrum and a guest component that not only blueshifts the near-infrared absorption of the acceptor but also improves electrical and morphological properties of the BHJ. A 2D photonic-structured antireflection coating is further developed to selectively improve the light absorption of IOPVs, leading to a PCE of 29.07% under 1000 lux LED illumination. More importantly, the antireflection coating maintains the initial PCE even when irradiated by light incident at large angles, demonstrating an omnidirectional effectiveness. This weaker angular dependency on light absorption provides practical prospects for future sustainable indoor photovoltaic systems.