In this study, the effect of electrode shape difference on the height of the Schottky barrier and the electric field in flexible photodiodes (PDs) has been investigated. For this purpose, three different electrode designs were prepared on three flexible FR4 layers that were coated with Zinc Oxide (ZnO). The printing circuit board (PCB) method was used to create these copper electrodes. The asymmetry of the PD electrodes and the difference in the height of the Schottky barrier has led to the creation of self-powered PDs. The effect of the amount and shape of the distribution of internal electric fields generated in the PDs and its effect on the parameters of the PDs has been investigated with the help of simulations performed in COMSOL software. The photocurrent of the sample with circular and rectangular electrodes was equal to 470 µA in 15 V bias, which was twice as good as a sample with an interdigitated MSM structure. Also, this sample had the best response time among these three samples, which was equal to 440 ms.

Three metal-semiconductor-metal (MSM) ultraviolet flexible self-powered photodiode (PDs) were fabricated, which differed in the shape of the electrodes. Here, the effect of the electrode's shape on the height of the Schottky barrier and the electric field in these PDs was investigated. They were prepared based on porous Zinc Oxide (ZnO) on fiberglass. Different shapes of the electrodes affect the height of the Schottky barrier in each metal-semiconductor contact and provide the basis for the formation of self-powered PDs. It also affects the electric field generated in the PD's bias condition and affects the PD's parameter. They were fabricated using the radio frequency (RF) sputtering technique, and copper electrodes with different shapes and a sample with interdigitated electrodes were created using the printed circuit board (PCB) method. The photocurrent of the sample with circular and rectangular electrodes was equal to 470 μA in 15V bias, which was twice as good as a sample with an interdigitated MSM structure. It also had the best photocurrent at 0V, which is equal to 0.8 μA. This sample had the best response time among these three samples, which was equal to 440 ms. It is noteworthy that the simulation data confirmed the practical results.

In this study, three flexible metal–semiconductor–metal ultraviolet photodetectors are fabricated on the FR4 fiberglass substrate based on the porous zinc oxide by radiofrequency sputtering. Their copper electrodes were created by printed circuit board, a simple and cheap method. Here, the effect of porosity on the photodetector parameters is discussed. The results show that the difference in the finger size in the photodetectors leads to differences in the parameters. In these photodetectors, as the fingers increase in length, dark current increases from 0.25 to 67.3 µA, photocurrent from 1.98 to 208 µA, and response time from 430 to 570 ms. Also, with expanding finger width, these parameters changed 18.48 µA, 26.8 µA, and 440 ms, respectively.