Premium
A facile light‐trapping approach for ultrathin GaAs solar cells using wet chemical etching
Author(s) -
Eerden Maarten,
Bauhuis Gerard J.,
Mulder Peter,
Gruginskie Natasha,
Passoni Marco,
Andreani Lucio C.,
Vlieg Elias,
Schermer John J.
Publication year - 2020
Publication title -
progress in photovoltaics: research and applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.286
H-Index - 131
eISSN - 1099-159X
pISSN - 1062-7995
DOI - 10.1002/pip.3220
Subject(s) - materials science , ohmic contact , optoelectronics , isotropic etching , layer (electronics) , short circuit , solar cell , etching (microfabrication) , energy conversion efficiency , luminescence , optics , nanotechnology , voltage , physics , quantum mechanics
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.