Double-graded bandgap in Cu(In,Ga)Se-2 thin film solar cells by low toxicity selenization process

Yi Chih Wang, Han-Ping Shieh

Research output: Contribution to journalArticle

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Abstract

A low-toxic selenization with post gallium diffusion (PGD) treatment has been demonstrated to increase the bandgap in the surface Cu(In,Ga)Se-2 (CIGSe) absorbers and to form double-graded bandgap profiles to improve the cell efficiency. The CIGSe absorber with PGD for 5 min increased open-circuit voltage from 0.49 to 0.66V and efficiency from 9.2% to 13.2%, contributed by the enhancement of carrier recombination in the space-charge region. The reduction in short-circuit current from 30.8 to 29.9 mA/cm(2), attributed to the absorption loss in long-wavelength regions, can be potentially improved by further optimization of the minimum bandgap value in gradient valley. (C) 2014 AIP Publishing LLC.
Original languageEnglish
Article number073901
JournalApplied Physics Letters
DOIs
StatePublished - 18 Aug 2014

Keywords

  • ABSORBERS; MORPHOLOGY; DIFFUSION; PRECURSOR; GALLIUM; SURFACE

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