Hole Transport Layer Free Perovskite Light-Emitting Diodes With High-Brightness and Air-Stability Based on Solution-Processed CsPbBr3-Cs4PbBr6 Composites Films

Abstract

Recently, perovskite light-emitting diodes (PeLEDs) have drew widespread attention due to their high efficiencies. However, because of the sensitivity to moisture and oxygen, perovskite luminescent layers are usually prepared in high-purity nitrogen environment, which increases the cost and process complexity of device preparation and seriously hindrances its commercialization of PeLED in lighting and display application. Herein, dual-phase all-inorganic composite CsPbBr3-Cs4PbBr6 films are fabricated from CsBr-rich perovskite solutions by a simple one-step spin-coating method in the air with high humidity. Compared with the pure CsPbBr3 film, the composite CsPbBr3-Cs4PbBr6 film has much stronger photoluminescence emission and longer fluorescence lifetime, accompanied by increased photoluminescence quantum yield (33%). As a result, we obtained green PeLED devices without hole transport layer exhibiting a maximum brightness of 72,082 cd/m2 and a maximum external quantum efficiency of about 2.45%, respectively. More importantly, the champion device shows excellent stability with operational half-lifetime exceeding 1,000 min under continuous operation in the air. The dual-phase all-inorganic composite CsPbBr3-Cs4PbBr6 film shows attractive prospect for advanced light emission applications.

Self‐Assembled Molecule Doping Enables High‐Efficiency Hole‐Transport‐Layer‐Free Perovskite Light‐Emitting Diodes

“…[15] Yuan et al prepared a CsPbBr 3 -Cs 4 PbBr 6 composite film with 33% photoluminescence quantum yield (PLQY) in atmospheric environment by precise regulation of the molar ratio of PbBr 2 and CsBr, and the corresponding green-emitting PeLED device without the HTL delivered a maximum luminance of 72 082 cd m −2 and an EQE of 2.45%. [16] Li et al adopted quasi-2D perovskite with selfformed vertically graded distribution composition to fabricate the HTL-free PeLEDs and obtained an EQE of 9%. [17] However, the EQE of all these reported HTL-free PeLEDs is less than 10%, as summarized in Table S1 (Supporting Information), which is significantly lower than that of the conventional p-i-n or n-i-p type devices.…”

“…prepared a CsPbBr 3 ‐Cs 4 PbBr 6 composite film with 33% photoluminescence quantum yield (PLQY) in atmospheric environment by precise regulation of the molar ratio of PbBr 2 and CsBr, and the corresponding green‐emitting PeLED device without the HTL delivered a maximum luminance of 72 082 cd m −2 and an EQE of 2.45%. [ 16 ] Li et al. adopted quasi‐2D perovskite with self‐formed vertically graded distribution composition to fabricate the HTL‐free PeLEDs and obtained an EQE of 9%.…”