Electric-Field-Assisted Co-Deposition of Bacteriorhodopsin and PEDOT:PSS on Interdigitated Electrodes for Biohybrid Photodetectors.

This work presents the fabrication and characterization of biohybrid optoelectronic devices based on the integration of bacteriorhodopsin (bR) and PEDOT:PSS on interdigitated electrodes (IDEs). A three-phase methodology was developed to systematically optimize the active layer. First, the effect of an electric field applied during PEDOT:PSS drying was investigated, identifying a drying voltage of 1.2 V as the optimum among the tested conditions, achieving a maximum responsivity of (35.65±1.36) mA/W, a minimum noise equivalent power of (5.99±0.13)×10-10 W·Hz-1/2, and a maximum specific detectivity of (3.55±0.07)×108 cm Hz1/2W-1. Second, the compatibility of a physiological buffer for bR stabilization was assessed, demonstrating that a 60% PEDOT:PSS/40% buffer composition preserved and further improved the optoelectronic performance of the polymer matrix. Finally, bacteriorhodopsin was incorporated into the optimized PEDOT:PSS/buffer formulation, yielding the hybrid bR_1.2V_60% device, which exhibited an on/off ratio of 2.45 at 0 V and a maximum responsivity of (5.63±0.76) mA/W under reverse bias. Morphological analysis suggested improved film homogeneity, together with a continuous polymer matrix containing dispersed crystalline buffer-salt inclusions. Dynamic measurements showed a stable and reversible short-term photoresponse over successive illumination cycles (ΔION=18.54±0.17μA) with full baseline recovery. These results demonstrate a scalable strategy for the development of biohybrid photodetectors with potential for low-power and sustainable optoelectronic applications.