Structural Simplification of High-Bandwidth Organic Photodiodes for Next-Generation Optical Wireless Communication

Next-generation optical wireless communication (OWC) networks require exceptionally fast receiving elements. While organic photodetectors (OPDs) offer advantages like tunable absorption and large-area processability, their high-speed deployment is hindered by narrow bandwidths stemming from low carrier mobility and high RC time constants. Traditional complex, multi-layered OPD designs maximize quantum efficiency but inevitably increase series resistance, prolong transit times, and introduce signal-delaying trap states. To overcome these limitations, this study introduces a dramatically simplified, vacuum-evaporated OPD architecture. By intentionally reducing structural complexity and precisely thinning the constituent layers, we minimize series resistance and balance geometric capacitance, effectively suppressing the RC delay that impedes high-speed switching. Consequently, our streamlined OPD achieves an expanded cut-off frequency exceeding 1 MHz, demonstrating that optimized physical simplicity yields high-fidelity, rapid signal conversion. This robust temporal response is highly conducive to parallel data processing and multichannel integration, seamlessly supporting scalable spatial multiplexing systems and high-density receiver arrays where uniform, rapid channel responses are mandatory. Furthermore, the vacuum-evaporated structure's simplicity directly translates into enhanced manufacturing reproducibility and higher device yields. Ultimately, this work establishes a robust foundation for integrating organic optoelectronics into future OWC networks, paving the way for efficient, large-area array systems capable of meeting the stringent demands of high-bandwidth data transmission.