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. 2022 Jan 21:10:828322.
doi: 10.3389/fchem.2022.828322. eCollection 2022.

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

Fang Yuan  1 , Min Zhang  1 , Chunrong Zhu  1 , Xiaoyun Liu  1 , Chenjing Zhao  1 , Jinfei Dai  1 , Hua Dong  1 , Bo Jiao  1 , Xuguang Lan  2 , Zhaoxin Wu  1   3
Affiliations

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

Fang Yuan et al. Front Chem. .

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.

Keywords: CsPbBr3-Cs4PbBr6 composites; all-inorganic perovskites; device stability; dual-phase; perovskite light-emitting diodes.

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Conflict of interest statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Figures

FIGURE 1
FIGURE 1
Top view SEM images of the corresponding all-inorganic perovskite films with different molar ratios of PbBr2 and CsBr, such as (A) 1:0.8, (B) 1:1.0, (C) 1:1.1 (D) 1:1.3, (E) 1:1.5, (F) 1:1.7, respectively. The scale bar is 2 μm in all images.
FIGURE 2
FIGURE 2
Bragg-Brentano X-ray diffraction patterns for the corresponding all-inorganic perovskite films with different molar ratios of PbBr2 and CsBr, such as 1:0.8, 1:1.0, 1:1.1, 1:1.3, 1:1.5, 1:1.7, respectively. The right of the figure shows the crystal structures of CsPbBr3 (bottom) and Cs4PbBr6 (top) perovskite.
FIGURE 3
FIGURE 3
(A) The steady-state PL spectra and (B) time-resolved photoluminescence (TRPL) measurements of the corresponding all-inorganic perovskite films with different molar ratios of PbBr2 and CsBr, such as 1:0.8, 1:1.0, 1:1.1, 1:1.3, 1:1.5, 1:1.7, respectively.
FIGURE 4
FIGURE 4
(A) Device configuration and (B) cross sectional SEM image of the PeLED based on the all-inorganic perovskite film with the molar ratio of PbBr2 to CsBr = 1:1.5. (C) Energy band diagram of the perovskites and PeLED devices.
FIGURE 5
FIGURE 5
(A) Current density-voltage (J-V), (B) luminance-voltage (L-V), (C) current efficiency-voltage (CE-V), (D) EQE-voltage (EQE-V) of the PeLED devices based on the perovskite films doped with different molar ratios of PbBr2 and CsBr, such as 1:0.8, 1:1.0, 1:1.1, 1:1.3, 1:1.5, 1:1.7, respectively.
FIGURE 6
FIGURE 6
(A) EL spectra of the PeLED device based on the all-inorganic perovskite film with the molar ratio of PbBr2 to CsBr = 1:1.5 operating under different applied voltages. The inset shows its normalized EL and PL spectra, as well as its digital photographs in operation at 6 V. (B) CIE chromaticity coordinate diagram, (C) histogram of maximum luminance, (D) stability test under continuously operational conditions for the PeLED device based on the all-inorganic CsPbBr3-Cs4PbBr6 perovskite film with the molar ratio of PbBr2 to CsBr = 1:1.5.
See this image and copyright information in PMC

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