Bifunctionally Driven Organic Photonic Conversion Devices Facilitated by Minimalistic Synthesis‐Based Interfacial Energetic Alignment

Bifunctional integration of indoor organic photovoltaics (OPVs) and photodetectors (OPDs) faces fundamental challenges because of incompatible interfacial thermodynamics: indoor OPVs require unimpeded charge extraction under low-light conditions (200-1000 lx), whereas OPDs require stringent suppression of noise current. Conventional hole transport layers (HTLs) fail to satisfy these opposing charge-dynamic requirements concurrently with commercial practicality (large-area uniformity, photostability, and cost-effective manufacturability). This study introduces benzene-phosphonic acid (BPA)-a minimalist self-assembled monolayer (SAM)-based HTL with a benzene core and phosphonic acid anchoring group-enabling cost-effective synthesis and excellent ITO interfacial properties such as energy alignment, uniform monolayer, and stability. This molecular design resolves core limitations and achieves high indoor OPV efficiency (28.6% PCE at 1000 lx LED 2700 K), maintains 93% PCE retention when scaled by ≈220× area, and delivers competitive self-powered (V = 0 V) OPD performance (noise equivalent power = 584 fW at bandwidth = 1 Hz and wavelength = 730 nm; 3 dB frequency = 103 kHz). Simplified synthesis of BPA reduces production costs by 720% ($0.042 cm^-2) and achieves 9× higher power-per-cost ratio (19.25 mW∙$^-1) relative to its counterpart SAM. Synergy between performance and commercial practicality positions BPA-HTL as a transformative enabler for self-powered IoT and wearable optoelectronics.