| 1. |
- Phung, Nga, et al.
(författare)
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Photoprotection in metal halide perovskites by ionic defect formation
- 2022
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Ingår i: Joule. - : Elsevier BV. - 2542-4351. ; 6:9, s. 2152-2174
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Tidskriftsartikel (refereegranskat)abstract
- Photostability is critical for long-term solar cell operation. While light-triggered defects are usually reported as evidence of material degradation, we reveal that the formation of certain defects in metal halide perovskites is crucial for protection against intense or prolonged light exposure. We identify an inherent self-regulating cycle of formation and recovery of ionic defects under light exposure that mitigates the overheating of the lattice due to hot carrier cooling, which allows exposure to several thousand suns without degrading. The excess energy instead dissipates by forming defects, which in turn alters the optoelectronic properties of the absorber, resulting in a temporary reduction of photon absorption. Defects gradually recover to restore the original optoelectronic properties of the absorber. Photoprotection is a key feature for the photostability in plants. Thus, finding a protection mechanism in metal halide perovskites similar to those in nature is encouraging for the development of long-term sustainable solar cells.
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| 2. |
- Phung, Nga, et al.
(författare)
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The Role of Grain Boundaries on Ionic Defect Migration in Metal Halide Perovskites
- 2020
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Ingår i: Advanced Energy Materials. - : Wiley. - 1614-6832 .- 1614-6840. ; 10:20
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Tidskriftsartikel (refereegranskat)abstract
- Halide perovskites are emerging as revolutionary materials for optoelectronics. Their ionic nature and the presence of mobile ionic defects within the crystal structure have a dramatic influence on the operation of thin-film devices such as solar cells, light-emitting diodes, and transistors. Thin films are often polycrystalline and it is still under debate how grain boundaries affect the migration of ions and corresponding ionic defects. Laser excitation during photoluminescence (PL) microscopy experiments leads to formation and subsequent migration of ionic defects, which affects the dynamics of charge carrier recombination. From the microscopic observation of lateral PL distribution, the change in the distribution of ionic defects over time can be inferred. Resolving the PL dynamics in time and space of single crystals and thin films with different grain sizes thus, provides crucial information about the influence of grain boundaries on the ionic defect movement. In conjunction with experimental observations, atomistic simulations show that defects are trapped at the grain boundaries, thus inhibiting their diffusion. Hence, with this study, a comprehensive picture highlighting a fundamental property of the material is provided while also setting a theoretical framework in which the interaction between grain boundaries and ionic defect migration can be understood.
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