Designing a Ternary Photovoltaic Cell for Indoor Light Harvesting with a Power Conversion Efficiency Exceeding 20%
Abstract
We use several polymers as the ternary component to demonstrate a ternary strategy to improve the performance of PCDTBT:PC71BM devices under 1-Sun and indoor illuminances. 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). However, with a ternary BHJ cell of PCDTBT:PDTSTPD:PC71BM, the PCE can be enhanced to 20.8%. FFs are the main improvements. 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 edge of the BHJ films.