Efficient Perovskite Light-Emitting Diodes by Buried Interface Modification with Triphenylphosphine Oxide

Metal halide perovskite films are prepared mainly by solution-based methods. However, the preparation process is prone to produce massive defects at the interface between the perovskite emitting layer and the charge transport layers, limiting the perovskite light-emitting diode device performance. Aiming at this problem, researchers have proposed many effective strategies to passivate these interface defects. However, most previous research studies only focus on modifying the perovskite top interface, and very few reports deal with the buried interface. Here, we deposited triphenylphosphine oxide (TPPO) molecules between the perovskite and the hole transport layer (HTL) and realized the buried interface modification. Adding TPPO avoids the contact recombination of the perovskite and HTL and improves the film quality by increasing the substrate wettability. Moreover, the lone pair electrons of P=O can interact with the uncoordinated lead (Pb2+) of the perovskite and passivate halogen vacancy defects, and the insulation property of TPPO helps to balance the injection of holes and electrons. As a result, a maximum external quantum efficiency (EQEmax) of 21.01% was obtained with an average of 18.4 +/- 0.9% over 30 devices, and the device reproducibility was greatly enhanced.

Automated summary

Metal halide perovskite films are commonly prepared using solution-based methods, but this can result in defects at the interface between the perovskite layer and charge transport layers, which limits the performance of perovskite light-emitting diodes. Researchers have proposed strategies to address this issue, but most studies focus on modifying the top interface rather than the buried interface. In this study, triphenylphosphine oxide (TPPO) molecules were deposited at the buried interface between the perovskite and hole transport layer, improving film quality and passivating halogen vacancy defects. This led to a maximum external quantum efficiency of 21.01% and enhanced device reproducibility.