Efficient Light Absorption in Organic Solar Cells Based on Two-Dimensional Arrayed Dielectric Nanospheres

Abstract

We have designed a patterned OSC based on 2-D arrayed dielectric nanospheres loaded on the indium tin oxide anode with other functional layers conformally embossed in the same profile as the nanosphere array. This design shows an integrated light absorption efficiency of 76.6% in the PSBTBT:PC71BM active layer over the wavelength range from 400 to 900 nm at normal incidence, outperforming the structurally identical planar control cell by 21.6%. Detailed investigations reveal that the excitation of photonic modes including the hybridization of cavity modes and Bloch modes, plasmonic modes, and their mutual coupling are responsible for the observed broadband enhancement in light absorption. Among them, the photonic modes are confirmed to be main contributor at most of the absorption band of PSBTBT:PC71BM, whereas at the absorption band edge of PSBTBT:PC71BM, the plasmonic resonance joins with the photonic resonances, collaboratively producing an enhancement factor as high as 110%. Moreover, the broadband absorption enhancement of our proposal is insensitive to the incident angle, favoring the practical application. This work provides a low cost and efficient route for achieving high-performance OSCs in experiment.