Disorder-order transition-induced unusual bandgap bowing effect of tin-lead mixed perovskites.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 39772692.
- Also identified by DOI 10.1126/sciadv.ads4038 and PMC identifier 11708898.
- Licence recorded as CC BY-NC.
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Abstract
Owing to the predominant merit of tunable bandgaps, tin-lead mixed perovskites have shown great potentials in realizing near-infrared optoelectronics and are receiving increasing attention. However, despite the merit, there is still a lack of fundamental understanding of the bandgap variation as a function of Sn/Pb ratio, mainly because the films are easy to segregate in terms of both composition and phase. Here, we report a fully stoichiometric synthesis of monocrystalline FAPb<sub>1-<i>x</i></sub>Sn<i><sub>x</sub></i>I<sub>3</sub> nanocrystals as well as their atomic-scale imaging. On the basis of the systematic measurements of the monocrystalline materials, strain and Coulomb interaction-induced atomic ordering was revealed to be responsible for the unusual discontinuous bandgap jumping near <i>x</i> = 0.5 from the expected bowing effect. As a result, both FAPb<sub>0.6</sub>Sn<sub>0.4</sub>I<sub>3</sub> and FAPb<sub>0.4</sub>Sn<sub>0.6</sub>I<sub>3</sub> have the lowest bandgaps of around 1.27 electron volts, while that of FAPb<sub>0.5</sub>Sn<sub>0.5</sub>I<sub>3</sub> is 1.33 electron volts. Correspondingly, their based light-emitting diodes can emit infrared lights with the wavelengths reaching 930 nanometers.