Enhanced efficiency of graded-bandgap thin-film solar cells due to concentrated sunlight

Faiz Ahmad, Akhlesh Lakhtakia, Peter B. Monk

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


A systematic study was performed with a coupled optoelectronic model to examine the effect of the concentration of sunlight on the efficiencies of CIGS, CZTSSe and AlGaAs thin-film solar cells with a graded-bandgap absorber layer. Efficiencies of 34.6% for CIGS thin-film solar cells and 29.9% for CZTSSe thin-film solar cells are predicted with a concentration of 100 suns, the respective one-sun efficiencies being 27.7% and 21.7%. An efficiency of 36.7% is predicted for AlGaAs thin-film solar cells with a concentration of 60 suns, in comparison to 34.5% onesun efficiency. Sunlight concentration does not affect the per-sun electron-hole-pair (EHP) generation rate but reduces the per-sun EHP recombination rate either near the front and back faces or in the graded-bandgap regions of the absorber layer, depending upon the semiconductor used for that layer, and this is the primary reason for the improvement in efficiency. Other effects include the enhancement of open-circuit voltage, which can be positively correlated to the higher short-circuit current density. Sunlight concentration can therefore play a significant role in enhancing the efficiency of thin-film solar cells.

Original languageEnglish (US)
Pages (from-to)10570-10578
Number of pages9
JournalApplied optics
Issue number34
StatePublished - Dec 1 2021

All Science Journal Classification (ASJC) codes

  • Atomic and Molecular Physics, and Optics
  • Engineering (miscellaneous)
  • Electrical and Electronic Engineering


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