Ultrafast self-trapping of photoexcited carriers sets the upper limit on antimony trisulfide photovoltaic devices.

Author(s) Yang, Z.; Wang, X.; Chen, Y.; Zheng, Z.; Chen, Z.; Xu, W.; Liu, W.; Yang, Y.Michael; Zhao, J.; Chen, T.; Zhu, H.
Journal Nat Commun
Date Published 2019 Oct 04

Antimony trisulfide (SbS) is considered to be a promising photovoltaic material; however, the performance is yet to be satisfactory. Poor power conversion efficiency and large open circuit voltage loss have been usually ascribed to interface and bulk extrinsic defects By performing a spectroscopy study on SbS polycrystalline films and single crystal, we show commonly existed characteristics including redshifted photoluminescence with 0.6 eV Stokes shift, and a few picosecond carrier trapping without saturation at carrier density as high as approximately 10 cm. These features, together with polarized trap emission from SbS single crystal, strongly suggest that photoexcited carriers in SbS are intrinsically self-trapped by lattice deformation, instead of by extrinsic defects. The proposed self-trapping explains spectroscopic results and rationalizes the large open circuit voltage loss and near-unity carrier collection efficiency in SbS thin film solar cells. Self-trapping sets the upper limit on maximum open circuit voltage (approximately 0.8 V) and thus power conversion efficiency (approximately 16 %) for SbS solar cells.

DOI 10.1038/s41467-019-12445-6
ISSN 2041-1723
Citation Nat Commun. 2019;10(1):4540.

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