Octupole Moment Driven Free Charge Generation in Partially Chlorinated Subphthalocyanine for Planar Heterojunction Organic Photodetectors

Abstract In this study, high-performance organic photodetectors (OPDs) are presented which utilize a pristine chlorinated subphthalocyanine (Cl 6 -SubPc) photoactive layer. Optical and optoelectronic analyses indicate that the device photocurrent is primarily generated through direct charge generation within the Cl 6 -SubPc layer, rather than exciton separation at layer interfaces. Molecular modelling suggests that this direct charge generation is facilitated by Cl 6 -SubPc’s high octupole moment (-80 DÅ 2 ), which generates a 200 meV shift in molecular energetics. Increasing the thickness of Cl 6 -SubPc leads to faster OPD response times, correlated with a decrease in trap density. Notably, PHJ OPDs with a 50 nm thick Cl 6 -SubPc photoactive layer exhibit detectivities approaching 10 13 Jones, with a dark current below 10 − 7 A cm − 2 up to -5 V. Based on these findings, we conclude that Cl 6 -SubPc is a promising material for high-performance OPDs employing a single-component photoactive layer.