Perovskite Photoluminescence: Direct Observation of Halide Migration and its Effect on the Photoluminescence of Methylammonium Lead Bromide Perovskite Single Crystals (Adv. Mater. 43/2017)

Contact Geometry and Pathway Determined Carriers Transport through Microscale Perovskite Crystals

“…Unlike Figure 5B, the PL intensity gradually increases from right to left (from cathode to anode), and the left‐most area (contact to the anode electrode) shows the maximum PL intensity. This observation is coherent with the previously reported observation, [ 59,60 ] in which the PL was enhanced in the bromide‐rich regions when Br − moves to the anode. With a close examination of the PL spectrum collected from three different points (marked in Figure 5E), it can be observed that the discrepancy of the PL peak positions increased significantly from 0.7 to 3.4 nm after applying a bias voltage.…”

“…This increased shifting of the PL peak position can be attributed to reabsorption, geometry‐dependent outcoupling efficiency, and polaron formation comprising Br‐migration‐induced distorted lattice and self‐trapped carriers. [ 59,61 ] The observations presented in Figure 5E,F confirm that the ion migration truly occurs upon a bias voltage in the microscale crystals.…”

“…It is reported that PL emission in MAPbBr 3 single crystals is related to defects because defects benefit charge carrier trapping and recombination leading to an enhanced PL emission. [ 58,59 ] Since the effective PL regime can be as deep as micrometers, [ 58 ] Figure 5B confirms that the defects density near edge is higher than the one in the crystal interior. Figure 5C shows the PL spectrum with normalized intensity collected from the three points as marked in Figure 5B before applying a voltage.…”

3D-to-2D Transition of Anion Vacancy Mobility in CsPbBr3 under Hydrostatic Pressure

“…In addition to electronic transport, LHPs are also well-known to exhibit significant ionic conductivity, even at moderate temperatures, − which is believed to arise primarily from the migration of highly mobile anion vacancies. − However, despite a number of recent studies indicating that the ionic conductivity of LHPs is significantly affected by stress, − and the fact that anion vacancy migration has been implicated as the underlying cause of a number of critical aspects of the behavior of LHP-based devices, such as current–voltage hysteresis − and long-term performance degradation, ,,− an atomistic understanding of the influence of stress on anion vacancy migration in LHPs is largely lacking. Furthermore, for the oxide perovskites, it is well established that different forms of stress modify activation enthalpies for anion vacancy migration significantly. − Given the soft nature of LHPs, such effects are likely to be at least as significant in those materials as in their oxide counterparts.…”

Interface passivation with Ti3C2Tx-MXene doped PMMA film for highly efficient and stable inverted perovskite solar cells

“…Several phenomena like ion-migration, phase segregation and defect generation are strongly influenced or increased by light. 71,72 To evaluate the effect of light and heat on the PSCs, we monitored encapsulated PSCs under the ISOS-L-2 protocol (Fig. 6(c)).…”