Optoelectronic Properties of Low‐Bandgap Halide Perovskites for Solar Cell Applications

• Published in: Advanced materials (Weinheim) 2021-10, Vol.33 (40), p.e2102300-n/a
• Main Authors: Dey, Krishanu, Roose, Bart, Stranks, Samuel D.
• Format: Article
• Language: English
• Subjects: Carrier recombination; defects; degradation; Doping; Energy conversion efficiency; Energy gap; lead–tin; low‐bandgap perovskites; Material properties; Optoelectronic devices; optoelectronics; Performance degradation; Perovskites; Photovoltaic cells; Solar cells
• ISSN: 0935-9648; 1521-4095
• DOI: 10.1002/adma.202102300

Riding on the coat tails of rapid developments in single‐junction halide perovskite solar cells, all‐perovskite multijunction solar cells have recently garnered significant attention, with the highest power‐conversion efficiency already reaching 25.6%. Much of this progress has been fueled by the rapid rise in the photovoltaic performance of low‐bandgap halide perovskite absorbers, materials, which, to date, have only been achievable by the partial or complete substitution of lead with tin. However, much room still exists to develop a more critical understanding of key material properties in these low‐bandgap perovskites. Herein, the key optoelectronic properties of absorption, carrier generation, recombination, and transport in these tin‐containing perovskites are discussed, showing that intrinsic doping distinctively impacts many of these properties, thereby rendering this class of halide perovskites unique within the family. Current understanding of the mechanisms that degrade optoelectronic performance in these materials and the corresponding devices are also summarized. These collective results highlight an important interplay between doping, defects, and degradation that will need to be controlled. Finally, the current gaps in understanding of these low‐bandgap perovskites are outlined, thereby providing guidelines for further research, which will unlock their full potential for realizing a plethora of high‐performance optoelectronic devices. Low‐bandgap tin‐containing halide perovskites have recently demonstrated impressive photovoltaic performances owing to their unique optoelectronic properties, which are yet to be fully explored. A perspective on the absorption, carrier generation, recombination, and transport phenomena in these materials is provided, underscoring an interesting interplay between doping, defects, and degradation that needs to be controlled for future optoelectronic applications.