Diffractive gratings for crystalline silicon solar cells-optimum parameters and loss mechanisms

Peters M, Rüdiger M, Hauser H, Hermle M, Bläsi B (2012)

Publication Type: Journal article

Publication year: 2012

Journal

Progress in Photovoltaics Wiley-Blackwell

Book Volume: 20

Pages Range: 862-873

Journal Issue: 7

DOI: 10.1002/pip.1151

Abstract

In this paper, we present guidelines for the design of backside gratings for crystalline silicon solar cells. We use a specially developed method based on a combination of rigorous 3D wave optical simulations and detailed semiconductor device modeling. We also present experimental results of fabricated structures. Simulation-based optimizations of grating period λ and depth d of a binary grating and calculations of the optical and electrical characteristics of solar cells with optimized gratings are shown. The investigated solar cell setup features a thickness of d bulk = 40 μm and a flat front surface. For this setup, we show a maximum increase in short-circuit current density of δj SC = 1.8 mA/cm 2 corresponding to an efficiency enhancement of 1% absolute. Furthermore, we investigate different loss mechanisms: (i) an increased rear surface recombination velocity S 0,b because of an altered surface caused by the introduction of the grating and (ii) absorption in the aluminum backside reflector. We analyze the trade-off point between gain due to improved optical properties and loss due to corrupted electrical properties. We find that, increasing the efficiency by 1% absolute due to improved light trapping, the maximum tolerable recombination velocity is S 0,b(max) = 5.2 × 10 3 cm/s. From simulations and measurements, we conclude that structuring of the aluminum backside reflector should be avoided because of parasitic absorption. Adding a dielectric buffer layer between silicon and the structured aluminum, absorption losses can be tuned. We find that for a planar reflector, the thickness of a SiO 2 buffer layer should exceed d SiO2 = 120 nm. Copyright © 2011 John Wiley & Sons, Ltd.

Involved external institutions

Fraunhofer-Institut für Solare Energiesysteme (ISE) / Fraunhofer Institute for Solar Energy Systems DE Germany (DE)

How to cite

APA:

Peters, M., Rüdiger, M., Hauser, H., Hermle, M., & Bläsi, B. (2012). Diffractive gratings for crystalline silicon solar cells-optimum parameters and loss mechanisms. Progress in Photovoltaics, 20(7), 862-873. https://doi.org/10.1002/pip.1151

MLA:

Peters, Marius, et al. "Diffractive gratings for crystalline silicon solar cells-optimum parameters and loss mechanisms." Progress in Photovoltaics 20.7 (2012): 862-873.

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