Phase Engineering for Highly Efficient Quasi-Two-Dimensional All-Inorganic Perovskite Light-Emitting Diodes via Adjusting the Ratio of Cs Cation

Abstract

Quasi-two-dimensional (2D) perovskites have received intensive attention as a new class of luminescent materials owing to large exciton binding energy and high photoluminescence efficiency. However, there usually contains a mixture of phases in these materials, and excessive low-dimensional phase perovskite is harmful for luminescence efficiency owing to the strong exciton-phonon quenching at the room temperature. Herein, a simple and effective method is proposed to suppress the growth of low-dimensional phase components in quasi-2D perovskite film via carefully adjusting the molar ratio of cesium bromide (CsBr) and phenylpropylammonium bromide (PPABr). The device based on this optimized film has achieved a peak brightness of 2921 cd m −2 and peak current efficiency of 1.38 cd A −1 , far away higher than that of the pristine CsPbBr 3 device. This research proves a new way for modulating the phase composition in quasi-2D perovskites to fabricate highly efficient perovskite light-emitting diodes (PeLEDs).

Phase control for quasi-2D blue emitters by spacer cation engineering

“…The obtained efficiency is significantly higher than that reported for PPA-Cs perovskite, where in all cases for different PPA:Cs ratios green emission was obtained and the highest efficiency achieved was 0.01%. 12 It should also be noted that FA-based devices exhibit multiple emission peaks consistent with the emission corresponding to n=2 phase and a large n or possibly 3D phase, while in MA-based devices we observe emission corresponding to n=3 phase, as illustrated in Fig. S10 †, Supporting Information.…”

High-Performance Quasi-2D Perovskite Light-Emitting Diodes Via Poly(vinylpyrrolidone) Treatment

“…3a, there exists a mass of pinholes in pure PPA 2 (CsPbBr 3 ) 2 PbBr 4 film with relatively large grains (≈ 30 nm) which could cause severe current leakage and then limit the device performance. According to the previous reports, the quality of perovskite films can be improved by the incorporation of polymers [10,30]. Indeed, according to Fig.…”

“…Hence, in our previous work, long-chain ammonium cation (phenylpropylammonium (PPA)) was introduced, enabling the formation of PPA 2 (CsPbBr 3 ) 2 PbBr 4 for quasi-2D PeLEDs through adjusting Cs ratio [30]. However, since there exist lots of pinholes in perovskite films, which cause serious leakage current, the performance of quasi-2D PeLEDs we reported still needs to be further improved for meeting the actual application.…”

Tailoring CsPbBr3 Growth Via Non-Polar Solvent Choice and Heating Method

“…All inorganic cesium lead halides (CsPbX3 , X = Cl, Br, I) and hybrid methylammonium lead halides (MAPbX3) are important functional materials [1][2][3][4][5] that can be synthesized as crystals, thinfilms, and nanomaterials with varied morphologies. 5,[6][7][8][9][10][11][12][13]14 Two dimensional (2D) plates and platelets are common, with thicknesses of only a few monolayers (ML) often observed, and lengths varied from nanometers to microns, which are formed during nucleation and growth, or self-assembled via solvent and or ligand mediated interactions. 4,[15][16][17][18][19][20] Studies have revealed that control over ligand types and stoichiometry, 20 as well as time and temperature of the synthesis can render various morphologies.…”