Sodium Ion Modifying In Situ Fabricated CsPbBr₃ Nanoparticles for Efficient Perovskite Light Emitting Diodes

Abstract

All‐inorganic perovskite has attracted much attention because of the higher stability. Many organic additives such as alkyl chain ammonium and polymers are usually introduced into perovskite to improve their performance. However, the long chain ammonium cations in perovskite may restrain the carrier transfer ability and ultimately deteriorate the performance of light‐emitting diodes (LEDs). In this work, the CsPbBr3 nanoparticles (NPs) are in situ fabricated by the synergistic effect of poly(ethylene oxide) and phenethylammonium bromide (PEABr). Particularly, sodium bromide (NaBr) with better conductivity is successfully introduced into CsPbBr3 NPs to substitute PEA partially, ultimately to passivate the defect and promote the carrier transfer ability. Besides, the addition of NaBr results in a better promotion for electron mobility than for hole mobility leading to a more balanced charge transport in devices. It enables NaBr based CsPbBr3 NPs green LEDs to exhibit a maximum external quantum efficiency (EQEmax) of 17.4%, which presents obvious enhancement compared to the LEDs without NaBr (EQEmax = 12%). Further, NaBr based CsPbBr3 NPs LEDs with a large area of 108 mm2 still show a high maximum EQE of 10.2%. Above all, this work provides a feasible way of adding metal additive in perovskite films to improve the performance of perovskite LEDs.

High‐Efficiency Formamidinium Lead Bromide Perovskite Nanocrystal‐Based Light‐Emitting Diodes Fabricated via a Surface Defect Self‐Passivation Strategy

“…Similar with the hole transport behavior, the electron transport capability is also improved in perovskite films with higher FABr ratio (Figure d). Specifically, the electron and hole mobilities are estimated with the same method as that used in our previous work . The electron and hole mobilities for NCs with different ratios of FABr are presented in Table S3 (Supporting Information), which reveals that the NCs with a FABr ratio of 2.2 show improved charge transport capability and more balanced charge transport.…”

Halide Perovskite Nanocrystal Emitters

“…Tremendous work has been done to improve the stability and performance of PNC‐based PeLED i) using short or zwitterionic sulfobetaine ligands in the PNCs synthesis, [ 185,186 ] 2) via metal ion doping to promote carrier injection ability of perovskites, [ 187,188 ] 3) upon addition of polymers, [ 189,190 ] 4) through surface passivation with metal halides/chlorides [ 178,180,191 ] or with a thin inorganic crystal layer at the grain boundary of PNCs to block ion migration, 5) via postsynthesis passivation (iminodibenzoic acid and didodecyldimethylammonium halides), [ 192,193 ] and finally 6) by optimizing the LED device structure, especially balancing the electron and the hole injection efficiency to reduce charge accumulation inside the device.…”

High-performance quasi-2D perovskite light-emitting diodes: from materials to devices

“…Simultaneously, a narrow full width at half maximum (FWHM) (<25 nm) is required. However, the pure red and blue quasi-2D PeLEDs still show lower efficiency, color purity, and stability than the desired values 84 , 88 – 91 . Here, we summarize three promising strategies to achieve high-performance pure red and blue quasi-2D PeLEDs.…”