Abstract
Quasi-two-dimensional (quasi-2D) Ruddlesden–Popper (RP) perovskites such as BA2Csn–1PbnBr3n+1 (BA = butylammonium, n > 1) are promising emitters, but their electroluminescence performance is limited by a severe non-radiative recombination during the energy transfer process. Here, we make use of methanesulfonate (MeS) that can interact with the spacer BA cations via strong hydrogen bonding interaction to reconstruct the quasi-2D perovskite structure, which increases the energy acceptor-to-donor ratio and enhances the energy transfer in perovskite films, thus improving the light emission efficiency. MeS additives also lower the defect density in RP perovskites, which is due to the elimination of uncoordinated Pb2+ by the electron-rich Lewis base MeS and the weakened adsorbate blocking effect. As a result, green light-emitting diodes fabricated using these quasi-2D RP perovskite films reach current efficiency of 63 cd A−1 and 20.5% external quantum efficiency, which are the best reported performance for devices based on quasi-2D perovskites so far.
Highlights
Metal halide perovskites exhibit distinctive properties such as tunable bandgaps and narrow emission linewidths, which are combined with low cost and facile solution processability[1,2,3,4,5,6,7,8,9,10]
Quasi-2D green perovskite LEDs (PeLEDs) fabricated following this strategy show current efficiency (CE) of 63 cd A−1 and up to 20.5% external quantum efficiency (EQE), making this device the bestperforming quasi-2D perovskite light-emitting diode (LED) reported in literature so far
CsMeS molecule consists of two parts: a Cs+ cation and a MeS− anion, whose molecular structure is shown in Supplementary Fig. 1
Summary
Metal halide perovskites exhibit distinctive properties such as tunable bandgaps and narrow emission linewidths, which are combined with low cost and facile solution processability[1,2,3,4,5,6,7,8,9,10]. The introduction of MeS in precursor solution can control the crystallization growth kinetics of quasi-2D perovskite films resulting in enhanced exciton energy transfer from small-n phases to large-n phases, which will be discussed below in detail.
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