Interlayer-dependent dual-mode response in OLED–UV photodetectors based on hybridized local and charge-transfer emitters

Abstract

Dual-mode organic devices that combine organic light-emitting diodes (OLEDs) with reverse-bias ultraviolet organic photodetectors (UVOPDs) must improve emissive efficiency without unduly compromising photocurrent generation and dark-current suppression. Herein, we use established hybridized local and charge-transfer (HLCT) blue emitters as a controlled platform to examine how interlayers influence this trade-off within a shared OLED-like architecture. Among the three HLCT emitters investigated, the PyIAnp-based device provides the most favorable baseline combination of OLED efficiency and reverse-bias photodetection response, delivering a maximum external quantum efficiency (EQEmax) of 8.07%, a responsivity of 6.79 mA W−1, and a detectivity of 2.88 × 1011 Jones at −0.5 V. Upon introducing an interlayer, the device characteristics improve further; in particular, TAPC yields the best combined response, increasing EQEmax to 10.24% while reducing the dark current density to 2.59 × 10−10 A cm−2, enhancing the responsivity to 19.99 mA W−1, and increasing detectivity to 2.19 × 1012 Jones at −0.5 V. The photoluminescence quantum yield (PLQY) and time-resolved photoluminescence (TRPL) measurements are consistent with reduced interfacial loss and a more favorable excited-state relaxation environment after TAPC insertion. Preliminary operational stability was also observed under the tested OLED and OPD conditions. These results show that interlayer selection provides a useful means of tuning interfacial processes in integrated OLED-like devices with reverse-bias ultraviolet photodetection functionality.