• Energy Research

Researchers in CUHK identified isolated non-fullerene acceptor (NFA) domains as the morphological origin of deep electron traps in organic photovoltaics. They showcased effective trap passivation by reducing the fractal dimensions of NFA networks.

Abstract 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 (-80 DÅ2), 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 -5 V. Based on these findings, we conclude that Cl6-SubPc is a promising material for high-performance OPDs employing a single-component photoactive layer.