Suppressing leakage current and charge accumulation via perovskite interface morphology regulation for efficient light-emitting diodes

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2024-09, Vol.495, p.153520, Article 153520
• Main Authors: Chen, Yongjian, Zeng, Xiankan, Yan, Cheng, Yang, Shiyu, Pan, Lunyao, Li, Chenglong, Mu, Maolin, Li, Wen, Tang, Guanqi, Yang, Weiqing
• Format: Article
• Language: English
• Subjects: Charge accumulation; Energy loss; Leakage current; Perovskite light-emitting diodes
• ISSN: 1385-8947
• DOI: 10.1016/j.cej.2024.153520

•Perovskite nanocrystals with smaller and more uniform size were synthesized.•Homogeneous perovskite emitting layer with lower roughness and better optical property was fabricated.•The effect of the emitting layer morphology on carrier dynamic behavior was elaborated from the perspective of capacitance and energetics.•Devices with luminance of 72941 cd/m2, EQE of 19.7 %, and CE of 94.3 cd/A were fabricated.•This work provided valuable insight into the impact of functional layer morphology on carrier dynamic behavior in PeLEDs. Charge carriers will recombine outside the emitting layer (EML) in non-ideal perovskite light-emitting diodes (PeLEDs), which can lead to parasitic loss and be detrimental to the performance of PeLEDs. Here, we have subtly utilized the property of perovskite nanocrystals (NCs) to design and optimize the homogeneity and optical property of EML, thereby suppressing the undesired carrier loss behavior in system. Photoluminescence (PL) spectra with transmission electron microscopy (TEM) images show that smaller and more homogeneous NCs in size are obtained by temperature-controlled (TC) method. Atomic force microscopy (AFM) images and temperature-dependent PL spectra show that EML with better optical property and uniformity is fabricated. The multiscale capacitance characterization shows that the device with modified EML exhibits significantly reduced leakage current, while the increased specific surface area between electron transport layer (ETL) and EML substantially reduces charge accumulation. Additionally, multiscale reactance, impedance and phase angle responses, reveal that the carrier oscillation behavior in the optimized device is suppressed compared to control group, leading to less energy loss. Consequently, the optimized devices exhibit lower leakage current and superior electroluminescent properties. The luminance is increased from 31650 cd/m2 to 72941 cd/m2, current efficiency (CE) is improved from 59.9 cd/A to 94.3 cd/A, and the external quantum efficiency (EQE) rises from 12.6 % to 19.7 %, corresponding to improvement of 230 %, 157 %, and 156 %, respectively. This research provides valuable insight into the impact of functional layer morphology on carrier dynamic behavior in PeLEDs.