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Title: Influence of defects and dopants on the photovoltaic performance of Bi 2S 3: First-principles insights

Bi 2S 3 has attracted extensive attention recently as a light-absorber, sensitizer or electron acceptor material in various solar cells. Using first-principles calculations, we find that the photovoltaic efficiency of Bi 2S 3 solar cells is limited by its intrinsic point defects, i.e., both S vacancy and S interstitial can have high concentration and produce deep defect levels in the bandgap, leading to non-radiative recombination of electron–hole carriers and reduced minority carrier lifetime. Unexpectedly most of the intrinsic defects in Bi 2S 3, including even the S interstitial, act as donor defects, explaining the observed n-type conductivity and also causing the high p-type conductivity impossible thermodynamically. Doping in Bi 2S 3 by a series of extrinsic elements is studied, showing that most of the dopant elements such as Cu, Br and Cl make the material even more n-type and only Pb doping makes it weakly p-type. Based on this, we propose that the surface region of n-type Bi 2S 3 nanocrystals in p-PbS/n-Bi 2S 3 nano-heterojunction solar cells may be type-inverted into p-type due to Pb doping, with a buried p–n junction formed in the Bi 2S 3 nanocrystals, which provides a new explanation to the longer carrier lifetime andmore » higher efficiency. Lastly, considering the relatively low conduction band and high n-type conductivity, we predict that Cu, Br and Cl doped Bi 2S 3 may be an ideal n-type electron acceptor or counter electrode material, while the performance of Bi 2S 3 as a light-absorber or sensitizer material is intrinsically limited.« less
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  1. East China Normal Univ., Shanghai (China)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  3. East China Normal Univ., Shanghai (China); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Publication Date:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Journal of Materials Chemistry. A
Additional Journal Information:
Journal Volume: 5; Journal Issue: 13; Journal ID: ISSN 2050-7488
Royal Society of Chemistry
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
OSTI Identifier: