Multifunctional hole transport layer enhances high-performance pure-red perovskite quantum-dot light-emitting diodes

The performance of perovskite light-emitting diodes (PeLEDs) has advanced rapidly; however, the development of suitable hole transport layers (HTLs) for PeLEDs remains a critical challenge. This study introduces a multifunctional HTL of poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt-(4,4′-(N-(4-[2-[2-(2-methoxyethoxy)ethoxy]ethoxy]phenyl)diphenylamine))] (TFTEG), which features a backbone similar to that of the commercial hole transport material poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt-(4,4′-(N-(4-sec-butylphenyl)diphenylamine))] (TFB), while its side chain is modified to include multiple ether groups. Theoretical calculations and experimental characterizations demonstrate that TFTEG not only significantly enhances hole injection but also effectively passivates uncoordinated Pb2+ defects at the buried interface through Lewis acid–base interactions. This substantially improves the photoluminescence and electroluminescence (EL) quantum yields of perovskite quantum dots (QDs). Pure-red quantum-dot PeLEDs that employ TFTEG as the HTL achieve a maximum external quantum efficiency of 9.67%, which signifies a substantial enhancement over the 4.56% efficiency observed in control devices utilizing the commercial TFB HTL. Furthermore, TFTEG contributes to a reduced turn-on voltage, enhanced brightness (1741 vs 888 cd m−2), and a stable EL spectrum peaking at 650 nm. The rapid response characteristics underscore its promising potential for high-speed optoelectronic applications, such as wireless communication systems.