This paper presents the results of a study on modified transimpedance amplifier circuits aimed at expanding their functionality. Using SPICE simulations, the impact of varying reference voltages on the output signal of the amplifiers was analyzed, allowing for the isolation and quantitative evaluation of the contributions of the photodiode and photo resistive conversion mechanisms. The results demonstrate that the proposed modifications enable the acquisition of informative signals carrying information about the photodiode and photoresistive components of the photocurrent. Additionally, it was found that the modifications affect the stability of transient processes and the impedance characteristics of the amplifiers. Based on the conducted research, a method for in-situ diagnostics of organic structures with the selection of the photodiode and photoresistive components of organic photostructures has been developed.