Low-cost, Deterministic Quasi-periodic Photonic Structures for light trapping in thin film silicon solar cells

Light trapping has been an important issue for thin film silicon solar cells because of the low absorption coefficient in the near infrared range. In this paper, we present a photonic structure which combines anodic aluminum oxide (AAO) and a distributed Bragg reflector (DBR) in the backside of thin film silicon. Simulation results show that this quasi-periodic AAO structure has a stronger light trapping effect than perfectly periodic diffractive gratings. As a proof of concept, we incorporated the backside structure into thick silicon PV cells. By comparing the measured photoconductance of silicon with different backside structures, the enhancement of light absorption near the band edge of silicon is demonstrated for our proposed light trapping structure.