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Development of arsenic doped Cd(Se,Te) absorbers by MOCVD for thin film solar cells / Ochai Oklobia, Giray Kartopu, S. Jones, P. Siderfin, B. Grew, Harrison Lee, Wing Chung Tsoi, Ali Abbas, J.M. Walls, D.L. McGott, M.O. Reese, Stuart Irvine

Solar Energy Materials and Solar Cells, Volume: 231, Start page: 111325

Swansea University Authors: Ochai Oklobia, Giray Kartopu, Harrison Lee, Wing Chung Tsoi, Stuart Irvine

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Abstract

Recent developments in CdTe solar cell technology have included the incorporation of ternary alloy Cd(Se,Te) in the devices. CdTe absorber band gap grading due to Se alloying contributes to current density enhancement and can result in device performance improvement. Here we report Cd(Se,Te) polycry...

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Published in: Solar Energy Materials and Solar Cells
ISSN: 0927-0248
Published: Elsevier BV 2021
Online Access: Check full text

URI: https://cronfa.swan.ac.uk/Record/cronfa57656
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Abstract: Recent developments in CdTe solar cell technology have included the incorporation of ternary alloy Cd(Se,Te) in the devices. CdTe absorber band gap grading due to Se alloying contributes to current density enhancement and can result in device performance improvement. Here we report Cd(Se,Te) polycrystalline thin films grown by a chamberless inline atmospheric pressure metal organic chemical vapour deposition technique, with subsequent incorporation in CdTe solar cells. The compositional dependence of the crystal structure and optical properties of Cd(Se,Te) are examined. Selenium graded Cd(Se,Te)/CdTe absorber structure in devices are demonstrated using either a single CdSe layer or CdSe/Cd(Se,Te) bilayer (with or without As doping in the Cd(Se,Te) layer). Cross-sectional TEM/EDS, photoluminescence spectra and secondary ion mass spectroscopy analysis confirmed the formation of a graded Se profile toward the back contact with a diffusion length of ~1.5 μm and revealed back-diffusion of Group V (As) dopants from the CdTe layer into Cd(Se,Te) grains. Due to the strong Se/Te interdiffusion, CdSe in the Se bilayer configuration was unable to form an n-type emitter layer in processed devices. In situ As doping of the Cd(Se,Te) layer benefited the device junction quality with current density reaching 28.3 mA/cm2. The results provide useful insights for the optimisation of Cd(Se,Te)/CdTe solar cells.
Keywords: CdTe, CdSe, Cd(Se,Te), Thin film, As doping, MOCVD, Solar cells, Photovoltaics
College: College of Engineering
Start Page: 111325