Rapid Recombination by Cadmium Vacancies in CdTe

Seán R. Kavanagh, Aron Walsh, David O. Scanlon

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

CdTe is currently the largest thin-film photovoltaic technology. Non-radiative electron-hole recombination reduces the solar conversion efficiency from an ideal value of 32% to a current champion performance of 22%. The cadmium vacancy (VCd) is a prominent acceptor species in p-type CdTe; however, debate continues regarding its structural and electronic behavior. Using ab initio defect techniques, we calculate a negative-U double-acceptor level for VCd, while reproducing the VCd hole-polaron, reconciling theoretical predictions with experimental observations. We find the cadmium vacancy facilitates rapid charge-carrier recombination, reducing maximum power-conversion efficiency by over 5% for untreated CdTe- A consequence of tellurium dimerization, metastable structural arrangements, and anharmonic potential energy surfaces for carrier capture.

Original languageEnglish
Pages (from-to)1392-1398
Number of pages7
JournalACS Energy Letters
Volume6
Issue number4
DOIs
StatePublished - 9 Apr 2021

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