Exciton-relaxation dynamics in lead halides

Abstract

We survey recent comprehensive studies of exciton relaxation in the crystals of lead halides. The luminescence and electron-spin-resonance studies have revealed that excitons in lead bromide spontaneously dissociate and both electrons and holes get self-trapped individually. Similar relaxation has been also clarified in lead chloride. The electron-hole separation is ascribed to repulsive correlation via acoustic phonons. Besides, on the basis of the temperature profiles of self-trapped states, we discuss the origin of luminescence components which are mainly induced under one-photon excitation into the exciton band in lead fluoride, lead chloride, and lead bromide.Comment: REVTeX, 5 pages, 5 figure

Structural origins of broadband emission from layered Pb–Br hybrid perovskites

“…Self-trapping of photogenerated carriers has previously been observed in polar dielectrics such as alkali halides, 32 – 34 lead halides, 35 , 36 and titania, 37 , 38 where strong electron–lattice coupling leads to carrier localization through large excited-state lattice distortions. 8 Broad PL features, similar to the broad emission we observed from (110) perovskites, 1 , 2 have been recently reported at room temperature from films of the (001) perovskite: (C 6 H 11 NH 3 ) 2 PbBr 4 .…”

“…Self-trapping has been extensively studied in alkali halides 32 – 34 and lead halides, 35 , 36 , 50 which exhibit a number of similarities to lead-halide perovskites, such as band-edge orbital composition. However, unlike in purely inorganic solids, we can induce slight distortions in the inorganic lattice of hybrid perovskites by fine tuning the organic cations.…”

Extrinsic nature of the broad photoluminescence in lead iodide-based Ruddlesden–Popper perovskites

“…In particular, a variety of chloride and bromide-based 2D perovskites have been shown to either give a combination of the NE and BE or to only show the latter 5,9,[11][12][13] . STEs have previously been invoked for the broad emission bands of a variety of materials [14][15][16][17][18] , but it is probably their observation in lead halides 19,20 and layered alkylammonium cadmium chlorides 21 that made researchers make the connection towards the current materials.…”

Role of electrochemical reactions in the degradation of formamidinium lead halide hybrid perovskite quantum dots

“…S7† shows the PL spectra of the film with different excitations that were absorbed by various lead halide plumbate complexes. 45–47 Interestingly, these spectra contain similar emission bands with different intensities. These bands were subsequently deconvoluted into three different PL peaks (Fig.…”

“…S8†) centered at 495, 538, and 578 nm, which were attributed to PbBr 2 , PbBr 4 2− , and PbBr 3 − species, respectively. 45,47 Therefore, the applied potential transformed the dispersed PQDs into various lead halide plumbate complexes, such as PbBr 2 , PbBr 4 2− , and PbBr 3 − .…”