The effects of poly[<i>N</i>,<i>N'</i>-bis(4-butylphenyl)-<i>N</i>,<i>N'</i>-bis(phenyl)-benzidine](Poly-TPD)/di-[4-(<i> <u>N</u> </i>,<i>N</i>-di-p-tolyl-amino)-phenyl]cyclohexane (TAPC) composite hole transport layer on the performance improvement

Hybrid organic–inorganic FAPbI3 has emerged as a highly promising material for near-infrared perovskite light-emitting diodes (NIR PeLEDs), with potential applications in biometric identification, biomedical imaging, and night vision technologies. However, FAPbI3-based flexible light-emitting diodes suffer from severe charge injection imbalance, where electron injection significantly exceeds hole injection, leading to exciton quenching and suboptimal device performance. To address this limitation, we propose a composite hole transport layer (HTL) to regulate charge injection and recombination dynamics. In this study, a composite HTL comprising Poly-TPD as the host matrix and 1,1-bis[4-[N,N'-bis(4-methylphenyl)amino]phenyl]cyclohexane (TAPC) as dopants at varying concentrations was employed. The optimized doping concentration resulted in a 34% enhancement in external quantum efficiency (EQE) compared to pristine poly-TPD. Furthermore, the integration of high-stability FAPbI3 quantum dots with the composite HTL demonstrated remarkable advantages for flexible optoelectronics, yielding a maximum current density of 631.4 mA/cm2, a peak EQE of 3.9%, and a maximum radiant flux of 13.7 W sr−1 m−2. Notably, the device retained 93% of its initial EQE even after 20 bending cycles, underscoring its mechanical robustness and potential for next-generation flexible display and sensing technologies.