Samsung Advanced Institute of Technology

In this study, high-performance organic photodetectors (OPDs) are presented which utilize a pristine chlorinated subphthalocyanine (Cl6-SubPC) photoactive layer. Optical and optoelectronic analyses indicate that the device photocurrent is primarily generated through direct charge generation within the Cl6-SubPC layer, rather than exciton separation at layer interfaces. Molecular modelling suggests that this direct charge generation is facilitated by Cl6-SubPC’s high octupole moment (-80DŲ), which generates a 200 meV shift in molecular energetics. Increasing the thickness of Cl6-SubPC leads to faster OPD response times, correlated with a decrease in trap density. Notably, PHJ OPDs with a 50 nm thick Cl6-SubPC photoactive layer exhibit detectivities approaching 1013 Jones, with a dark current below 10-7 A cm-2 up to -5V. Based on these findings, we conclude that high octupole moment molecular semiconductors are promising materials for high-performance OPDs employing a single-component photoactive layer.