Open AccessNanophotonic light trapping with patterned transparent conductive oxides
Author(s) -
Alok P. Vasudev,
Jon A. Schuller,
Mark L. Brongersma
Publication year - 2012
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.20.00a385
Subject(s) - materials science , nanophotonics , optoelectronics , plasmonic solar cell , silicon , optics , plasmon , amorphous silicon , thin film , layer (electronics) , reflection (computer programming) , crystalline silicon , nanotechnology , monocrystalline silicon , physics , computer science , programming language
Transparent conductive oxides (TCOs) play a crucial role in solar cells by efficiently transmitting sunlight and extracting photo-generated charge. Here, we show how nanophotonics concepts can be used to transform TCO films into effective photon management layers for solar cells. This is accomplished by patterning the TCO layer present on virtually every thin-film solar cell into an array of subwavelength beams that support optical (Mie) resonances. These resonances can be exploited to concentrate randomly polarized sunlight or to effectively couple it to guided and diffracted modes. We first demonstrate these concepts with a model system consisting of a patterned TCO layer on a thin silicon (Si) film and outline a design methodology for high-performance, TCO-based light trapping coatings. We then show that the short circuit current density from a 300 nm thick amorphous silicon (a-Si) cell with an optimized TCO anti-reflection coating can be enhanced from 19.9 mA/cm2 to 21.1 mA/cm2, out of a possible 26.0 mA/cm2, by using an optimized nanobeam array. The key differences and advantages over plasmonic light trapping layers will be discussed.