Reducing Defects in Halide Perovskite Nanocrystals for Light-Emitting Applications

Abstract

The large specific surface area of perovskite nanocrystals (NCs) increases the likelihood of surface defects compared to that of bulk single crystals and polycrystalline thin films. It is thus crucial to comprehend and control their defect population in order to exploit the potential of perovskite NCs. This Perspective describes and classifies recent advances in understanding defect chemistry and avenues toward defect density reduction in perovskite NCs, and it does so in the context of the promise perceived in light-emitting devices. Several pathways for decreasing the defect density are explored, including advanced NC syntheses, new surface-capping strategies, doping with metal ions and rare earths, engineering elemental compensation, and the translation of core–shell heterostructures into the perovskite materials family. We close with challenges that remain in perovskite NC defect research.

Purcell Enhancement and Wavelength Shift of Emitted Light by CsPbI3 Perovskite Nanocrystals Coupled to Hyperbolic Metamaterials

“…The PL peak wavelength for the reference sample is observed at around 705 nm, in good agreement with what is reported by other authors for films of CsPbI 3 PNCs at cryogenic temperatures. 57 , 63 We also tested CsPbBr 3 PNCs deposited on top of the same HMM, whose spontaneous emission is peaked at around 520 nm. For these emitters, we did not observed any decay time reduction from 300 down to 15 K. This effect is ascribed to the wavelength dependence of the Purcell factor as a function of the metal fill factor in the HMM, which is equal/smaller than 0.5 in our case and consequently exhibiting a negligible Purcell factor enhancement at around 500 nm (see refs ( 39 ) and ( 64 ) for example, and section 4 of the Supporting Information ).…”

Suppression of Electric Field-Induced Segregation in Sky-Blue Perovskite Light-Emitting Electrochemical Cells

“…All the prepared solutions contained a fixed weight ratio of PbBr to PEO as 5:4. In the meanwhile, CsCl:PbBr ratio was varied (1:1, 5:4, 4:3) to demonstrate that an excess of the monohalide salt taken for the perovskite production reduces the concentration of halide vacancies in perovskite crystals [ 34 , 35 ].…”

Device Engineering for All-Inorganic Perovskite Light-Emitting Diodes

“…In addition to the optimization of perovskite emitters, the PeLED performance has been greatly boosted by the innovation of device engineering. Currently, all-inorganic PeLEDs are also being explored in flexible as well as transparent optoelectronics, which further widen their general applications [241,242,243]. In addition, it can be easily predicted that all-inorganic PeLEDs will show higher performance by virtue of effective outcoupling technologies [244,245,246,247], despite negligible attention has been paid on the improvement of the outcoupling factor thus far.…”