Biocompatible bovine serum albumin dielectric layers for high-performance and neuromorphic n-type organic field-effect transistors

In this study, we systematically explore the role of bovine serum albumin (BSA) as a biocompatible interfacial modification layer in n-type organic field-effect transistors (OFETs) based on N, N′-ditridecylperylene-3,4,9,10-tetracarboxylic diimide (PTCDI-C₁₃). By varying BSA concentrations from 4.5 to 100 mg/ml, we demonstrate its significant influence on dielectric thickness, surface energy, and interface trap density. An optimal concentration of 9.0 mg/ml yields a favorable balance between surface smoothness and gate dielectric coupling, resulting in enhanced molecular ordering, reduced subthreshold swing (0.09 V/dec), and improved carrier mobility (0.7 cm²/V·s). Photoluminescence, Raman, and X-ray diffraction analyses confirm that BSA promotes π–π stacking and crystallographic alignment conducive to efficient charge transport. Furthermore, synaptic functionalities are realized in devices incorporating 4.5 and 9.0 mg/ml BSA layers, as evidenced by pronounced excitatory postsynaptic current (EPSC) responses. These findings highlight the potential of BSA as a multifunctional dielectric material for high-performance and neuromorphic organic electronic applications.