Coverage Contact Control of Benzoxazole-Based SAMs to Enhance the Operational Performance of Perovskite Nanocrystal Light–Emitting Diodes

Abstract

Perovskite light–emitting diodes (PeLEDs) have emerged as a prominent topic within optoelectronic research. Despite remarkable advancements, this technology still faces challenges that must be addressed for successful commercialization. Typical device architectures employ PEDOT:PSS as hole transporting material (HTM). However, besides its expensive cost, PEDOT:PSS has been reported to cause issues with efficiency and long-term stability. Molecular self-assembled monolayers (SAMs) have arisen as potential HTMs, not just to overcome these drawbacks but to enhance the interface properties and performance of LEDs. This technology has been efficiently applied in PeLEDs, but its use in devices based on perovskite nanocrystals (PNCs) remain underexplored. In this work, two benzoxazole derivatives have been analyzed as SAMs to conform the hole selective contact in CsPbBr₃ PNCs-based LEDs. The devices demonstrate improved optoelectronic properties compared to the reference composed of PEDOT:PSS, attributed to a suitable band alignment and an enhanced charge injection. Furthermore, optimizing the deposition technique of SAMs on the conducting substrate by dip- or spin-coating has allowed the preparation of efficient LEDs exhibiting external quantum efficiencies (EQEs) up to 6.8% with 300 s of operational stability. This research aims to provide extensive insights into applying SAMs to design PeLEDs with improved carrier mobility.