A facile light‐trapping approach for ultrathin GaAs solar cells using wet chemical etching. (18th December 2019)

• Record Type: Journal Article
• Authors: van Eerden, Maarten; Bauhuis, Gerard J.; Mulder, Peter; Gruginskie, Natasha; Passoni, Marco; Andreani, Lucio C.; Vlieg, Elias; Schermer, John J.
• Is Part Of: Progress in photovoltaics. Volume 28:Number 3(2020)
• Page Start: 200
• Page End: 209
• Publication Date: 2019-12-18
• Subjects: light trapping -- luminescence outcoupling -- textured III‐V solar cells -- ultra‐thin GaAs -- wet etching; Solar cells -- Periodicals; Photovoltaic cells -- Periodicals; Solar power plants -- Periodicals; 621.31245
• DOI: 10.1002/pip.3220
• Languages: English
• ISSNs: 1062-7995

Abstract

Abstract: Thinning down the absorber layer of GaAs solar cells can reduce their cost and improve their radiation hardness, which is important for space applications. However, the lighttrapping schemes necessary to achieve high absorptance in these cells can be experimentally challenging or introduce various parasitic losses. In this work, a facile light‐trapping approach based on wet chemical etching is demonstrated. The rear‐side contact layer of ultrathin GaAs solar cells is wet‐chemically textured in between local Ohmic contact points using an NaOH‐based etchant. The resulting contact layer morphology is characterized using atomic force microscopy and scanning electron miscroscopy. High broadband diffuse reflectance and haze factors are measured on bare and Ag‐coated textured contact layers. The textured contact layer is successfully integrated as a diffusive rear mirror in thin‐film solar cells comprising a 300‐nm GaAs absorber and Ag rear contact. Consistent increases in short‐circuit current density ( J SC ) of approximately 3 mA cm −2 (15%) are achieved in the textured cells, while the open‐circuit voltages and fill factors do not suffer from the textured rear mirror. The best cell achieves a J SC of 24.8 mA cm −2 and a power conversion efficiency of 21.4%. The textured rear mirror enhances outcoupling of luminescence at open circuit, leading to a strong increase in the external luminescent efficiency. Abstract : A novel light‐trapping scheme for ultrathin GaAs solar cells based on simple wet chemistry is reported. In comparison with 300‐nm‐thick planar reference solar cells, the wet chemically textured cells exhibit a 3 mA cm −2 (14%) increase in short‐circuit current and an increased external luminescent efficiency, leading to an efficiency of 21.4%.