High Performance Hole-Transporting-Layer Free Perovskite Light-Emitting Diodes by Incorporating Self-Assembled Molecules
Yin-Ti Lai a, Chu-Chen Chueh a
a Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan
Asia-Pacific International Conference on Perovskite, Organic Photovoltaics and Optoelectronics
Proceedings of Asia-Pacific International Conference on Perovskite, Organic Photovoltaics and Optoelectronics (IPEROP24)
Tokyo, Japan, 2024 January 21st - 23rd
Organizers: Qing Shen and James Ryan
Poster, Yin-Ti Lai, 101
Publication date: 18th October 2023

Metal halide perovskite light-emitting diode (PeLED) has drawn great interest in recent years due to its high luminescence efficiency, broad color tunability and solution processability. Recently, hole-transporting-layer-free (HTL-free) perovskite light-emitting diodes (PeLEDs) have attracted research attention due to the simplified device structure, fast fabrication process, and low production cost, which is beneficial to commercialization. However, the insufficient interfacial charge transport severely limits the efficiency of HTL-free PeLED, which is unfavorable for its application.

In this work, we demonstrated a self-assembled molecules (SAM) doping strategy with the organic small molecules with phosphonic acid anchoring group. We adopt different kinds of SAMs to verify the suitable one for PeLEDs. By directly doping SAM molecules into the perovskite precursor, these molecules will spontaneously self-assemble on the indium tin oxide substrate during the one-step perovskite film processing. The SAMs shift the work function of the ITO substrate to higher values due to the interfacial dipole they introduce, lowering the hole injection barrier and thus facilitating the injection, making the interfacial charge transport more effective and thus boosting the efficiency of our devices. The performance of the devices is greatly improved with the assistance of SAMs. For the best-performed one, the external quantum efficiency (EQE) is boosted from 4.5% to 13.98% with a 2.5-fold increase, and the brightness is improved from 20000 cd/m2 to 51000 cd/m2 at 512 nm due to its capability of shifting the work function to the most suitable level compared to other SAMs. The results demonstrate that this SAM doping strategy can be an effective way to prepare high-performance HTL-free PeLEDs.

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