Self‐Structural Healing of Encapsulated Perovskite Microcrystals for Improved Optical and Thermal Stability

Abstract

Perovskite materials and their optoelectronic devices have attracted intensive attentions in recent years. However, it is difficult to further improve the performance of perovskite devices due to the poor stability and the intrinsic deep level trap states (DLTS), which are caused by surface dangling bonds and grain boundaries. Herein, the CH 3 NH 3 PbBr 3 perovskite microcrystal is encapsulated by a dense Al 2 O 3 layer to form a microenvironment. Through optical measurement, it is found that the structure of perovskite can be healed by itself even under high temperature and long-time laser illumination. The DLTS density decreases nearly an order of magnitude, which results in 4-14 times enhancement of light emission. The observation is ascribed to the micron-level environment, which serves as a self-sufficient high-vacuum growth chamber, where the components of the perovskite are completely retained when sublimated and the decomposed atoms can re-arrange after thermal treatment. The modified structure showing high thermal stability is able to maintain excellent optical and lasing stability up to 2 years. This discovery provides a new idea and perspective for improving the stability of perovskite and can be of practical interest for perovskite device application.

Quasi-Type II Core–Shell Perovskite Nanocrystals for Improved Structural Stability and Optical Gain

“…Recent studies have been carried out for obtaining stable and high-performance perovskite materials by developing synthesis methods and post-treatments, such as doping, underlayer abduction, and additive additions. , Among them, the most effective approach is to cover other materials around PeNCs. − Researchers developed a facial method for coating a TiO 2 shell on PeNCs, greatly improving their stability . The resulting CsPbBr 3 /TiO 2 core–shell structures are ultrastable and exhibit excellent water stability of more than 12 weeks.…”

Donor–Acceptor Competition via Halide Vacancy Filling for Oxygen Detection of High Sensitivity and Stability by All‐Inorganic Perovskite Films

“…These results suggest that the Br vacancies indeed are located mainly at the GBs of CsPbBr 3 film, parallel to the previous studies of OIHPs reporting halide vacancies are most frequently found at GBs. [12,[31][32][33][34][35] To verify the oxygen adsorption by the Br vacancies at GBs, we further performed the DFT modeling and analyzed the charge distribution in the vicinity of the defect-free surface and the O 2 -occupied vacancy on CsPbBr 3 film (Figure 3f,g).…”

“…These results suggest that the Br vacancies indeed are located mainly at the GBs of CsPbBr 3 film, parallel to the previous studies of OIHPs reporting halide vacancies are most frequently found at GBs. [ 12,31–35 ]…”

Stabilization Techniques of Lead Halide Perovskite for Photovoltaic Applications

“…The organicinorganic alternating encapsulation layer fabricated from performance-undamaged processes exhibited a low water vapor transmittance rate of 1.3 Â 10 À5 g m À2 day À1 , enabling PSC based on it preserved 96% of initial PCE after storage under 30 C and 80% humidity for 2000 h. Besides moisture stability, the microenvironment in the ALD-deposited dense encapsulation layer may also enhance thermal and optical stability. [217] The encapsulants can offer extra functions beyond only protection. Bella et al used fluorinated photopolymer coatings as a strongly hydrophobic encapsulant toward environmental moisture on the front and back of solar cells.…”

“…The organic–inorganic alternating encapsulation layer fabricated from performance‐undamaged processes exhibited a low water vapor transmittance rate of 1.3 × 10 −5 g m −2 day −1 , enabling PSC based on it preserved 96% of initial PCE after storage under 30 °C and 80% humidity for 2000 h. Besides moisture stability, the microenvironment in the ALD‐deposited dense encapsulation layer may also enhance thermal and optical stability. [ 217 ]…”