Fullerene derivatives—Promising blue light absorbers suppressing visual hazards for efficient indoor light harvesters

With the rise of Internet of Things, indoor organic photovoltaic (IOPV) devices as the promising power supply unit of off-grid electronics have made great progress in recent years. However, as the only acceptable end-goal, their commercial large-scale production is still a long way off although the absolute efficiency values achieve significant breakthroughs and have exceeded 30%. One of the main obstacles to practical application is the impact of IOPV devices on human vision under indoor conditions. Because the IOPV devices usually require expansive areas deployed for larger output power under indoor cases, a semitransparent strategy is commonly adopted to reduce the effects on indoor light environments. Conventional semitransparent bulk heterojunctions (BHJs) with wide-bandgap donors and near-infrared absorbing acceptors generate a huge proportion of residual blue light, which may cause human visual fatigue and injury. Herein, we propose a fullerene derivative blending strategy to suppress the blue light hazards caused by the state-of-the-art IOPV devices and improve the overall device performance. A series of high-efficient non-fullerene BHJs were selected as model systems, and a low dosage of PC₇₁BM molecules can effectively reduce the blue light hazard efficacy (K_B,v). Furthermore, with the desirable electron transport property and strong absorbance of PC₇₁BM in the wavelength range of 400–500 nm, the ternary PM6:Y6:PC₇₁BM devices enjoy remarkably improved power conversion efficiencies. This work provides an effective approach to simultaneously suppress K_B,v values and improve performance of IOPV devices.