Designing a ternary photovoltaic cell for indoor light harvesting with a power conversion efficiency exceeding 20%

Abstract

We used several polymers as the ternary components to demonstrate a ternary strategy to improve the performance of PCDTBT:PC₇₁BM devices under 1 sun and indoor illumination. With a binary bulk-heterojunction (BHJ) of PCDTBT:PC₇₁BM organic photovoltaic (OPV) cell, a power conversion efficiency (PCE) of 16.5% under indoor light sources (300 lux from fluorescence tube) was achieved. However, with a ternary BHJ cell of PCDTBT:PDTSTPD:PC₇₁BM, the PCE can be enhanced to 20.8%. FFs are the primarily improved in these devices. Transport and absorption measurements indicate the origins of the improvements of OPV performance: the ternary BHJ films exhibit enhanced hole mobilities and reduced Urbach energies, indicating that the blending of the PDTSTPD component passivates shallow traps near the band edges of the BHJ films.