Intermediate-phase-assisted low-temperature formation of γ-CsPbI<sub>3</sub> films for high-efficiency deep-red light-emitting devices.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 32958808.
- Also identified by DOI 10.1038/s41467-020-18380-1 and PMC identifier 7505955.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Black phase CsPbI<sub>3</sub> is attractive for optoelectronic devices, while usually it has a high formation energy and requires an annealing temperature of above 300 °C. The formation energy can be significantly reduced by adding HI in the precursor. However, the resulting films are not suitable for light-emitting applications due to the high trap densities and low photoluminescence quantum efficiencies, and the low temperature formation mechanism is not well understood yet. Here, we demonstrate a general approach for deposition of γ-CsPbI<sub>3</sub> films at 100 °C with high photoluminescence quantum efficiencies by adding organic ammonium cations, and the resulting light-emitting diode exhibits an external quantum efficiency of 10.4% with suppressed efficiency roll-off. We reveal that the low-temperature crystallization process is due to the formation of low-dimensional intermediate states, and followed by interionic exchange. This work provides perspectives to tune phase transition pathway at low temperature for CsPbI<sub>3</sub> device applications.