Impedance spectroscopy of thin-film CdTe/CdS solar cells under varied illumination

Yuri Proskuryakov, Ken Durose, Mohammed Al Turkestani, Iván Mora-Seró, Germà Garcia-Belmonte, Francisco Fabregat-Santiago, Juan Bisquert, Vincent Barrioz, Daniel Lamb, Stuart Irvine, Eurig Jones

Research output: Contribution to journalArticlepeer-review

53 Citations (Scopus)

Abstract

The electrical properties of CdTe/CdS solar cells grown by metal organic chemical vapor deposition were investigated by a technique of impedance measurements under varied intensity of AM1.5 illumination. A generalized impedance model was developed and applied to a series of CdTe/CdS cells with variations in structure and doping. The light measurements were compared to the conventional ac measurements in dark under varied dc bias, using the same methodology for equivalent circuit analysis in both cases. Detailed information on the properties of the device structure was obtained, including the properties of the main p-n junction under light, minority carrier lifetime, back contact, as well as the effect of the blocking ZnO layer incorporated between the transparent conductor and CdS layers. In particular, the comparison between samples with different chemical concentrations of As has shown that the total device impedance and the series resistance are strongly increased at lower As densities, resulting in the lower collection current and efficiencies. At the same time the minority carrier lifetime was found to be one order of magnitude larger for the lowest value of As density, when compared to the optimized devices.
Original languageEnglish
Pages (from-to)044507
JournalJournal of Applied Physics
Volume106
Issue number4
DOIs
Publication statusPublished - 21 Aug 2009

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