Abstract: In Organic photodetector (OPD), the cathode interface layer, as a carrier transport medium, can effectively extract electrons, block holes to suppress charge recombination, and enhance the detection performance of the device. The regulation of its structure and physical properties has significant research value. Zinc oxide (ZnO) is currently a widely studied and applied interface layer material. Its preparation method mainly involves thermal annealing after spin-coating of the precursor solution. However, the method has problems such as limited control range of film thickness and morphology, and incompatibility with curved substrate. Based on this, it is proposed to prepare the ZnO cathode interface layer by electrochemical deposition, expand the controllable range of ZnO thin films, and achieve precise optimization of OPD performance. The dark current density of the device is as low as 5. 8 × 10^-9 A/cm² at a bias voltage of-0. 5V, and the peak external quantum efficiency (EQE) reaches 80. 35%. The specific detecibility (D^*) in the visible light band is all greater than 10¹² Jones. In addition, after adding the additive KCl to the electrolyte, the ultraviolet detection capability of the fabricated device was significantly enhanced. The EQE at 380 nm increased from less than 10% to 97%, and the D^* reached 2. 16 × 10¹² Jones. The method can provide a new solution for the precise regulation of OPD performance.