Combining randomly textured surfaces and one-dimensional photonic crystals as efficient light-trapping structures in hydrogenated amorphous silicon solar cells

Abstract

One of the foremost challenges in achieving high-efficiency thin-film silicon solar cells is in devising an efficient light trapping system because of the short optical path length imposed by the inherent thin absorption layers. In this paper, an efficient light trapping system is proposed using a combination of randomly textured surfaces and a one-dimensional photonic crystal (randomly textured photonic crystal; RTPC). The influence of the texture on the optical performance of RTPCs is discussed using the results of an experiment and a finite-difference time-domain simulation. This RTPC back reflector (BR) can provide high reflectivity and strong light scattering, resulting in an increased photocurrent density of the hydrogenated amorphous silicon (a-Si:H) solar cell. As a result, the highly textured RTPC BR yielded an efficiency of 9.6% for a-Si:H solar cell, which is much higher than the efficiency of 7.6% on flat AZO/Ag BR and 9.0% on textured AZO/Ag BR. This RTPC BR provides a new approach for creating high-efficiency, low-cost thin-film silicon solar cells.