Dual-Mode Organic Photodetectors with Optimized Charge Dynamics and Barrier Modulation for Superior Spectral...

Dual-mode organic photodetectors (OPDs) can enable intrinsic spectral selectivity without external filters, making them effective for imaging and sensing. This study analyzes the charge dynamics and engineering of both optical and electronic barriers to optimize the performance of the dual-mode OPD. To this end, this work controls the photoactive layer thickness to ensure selective photoresponse exclusively within the targeted wavelength (λ) range under each bias condition. Furthermore, this work introduces an electron-blocking CuSCN bilayer atop the intermediate hole transport layer (HTL) to suppress leakage current. The optimized dual-mode OPD achieves a linear dynamic range of 92.9 dB (at +3 V, λ = 515 nm) and 110 dB (at -3 V, λ = 730 nm), with a low root mean square noise current of 1.27 pA (at +3 V) and 241 fA (at -3 V), respectively. The specific detectivity reaches 3.24 × 10¹⁰ cm Hz^0.5W^-1 (at +3 V, λ = 515 nm) and 1.89 × 10¹¹ cm Hz^0.5W^-1 (at -3 V, λ = 730 nm) at 0.1 cm² and with 1 Hz bandwidth. These findings present a framework for the development of next-generation OPDs with enhanced spectral selectivity and minimized leakage current.