# Effect of Methylammonium Iodide (MACI) on MAPbI\({}_{3}\)-Based Perovskite UV-C Photodetectors
## 3 Results and Discussion
### Ultraviolet (UV) Detection Performance Evaluation of the Fabricated Photodetection Device  
The properties of MAPbI\({}_{3}\) PD doped with 0.10 M MACI can be investigated by irradiating the light of wavelength 254 nm with a light intensity of 0.774 mW/cm\({}^{2}\) in the dark experimental condition and analyzing the current-voltage (I-V) characteristics from \(-\)2 to +2 V. Figure 6 indicates the generated photocurrent depending on the mixture of Br\({}^{-}\). The generation of the photocurrent is affected by the intensity of the irradiated light and the bias voltage. The photocurrents generated at a voltage of 2 V were 36.8, 56.2, 76.2, 91.5, 115.2, and 80.9 uA, respectively, for the addition of FABr 0, FABr 5, FABr 10, FABr 15, FABr 20, and FABr 25. As the ratio of Br\({}^{-}\) increases, the amount of photocurrent generated increases. As can be seen in the previous pictures, this is because the extinction coefficient increased as the film gained structural stability. At the point where the photocurrent decreases again, it can be seen that excessive addition of anions has occurred. This suggests that an appropriate composition ratio is necessary for improved properties of the film. Figure 7a shows the responsivity (R) and detectivity (D) of as-prepared films. R represents the response efficiency of the fabricated PDs to the irradiated UV light. As the FABr content increased from FABr 0 to FABr 20, the R values increased to 24.5, 37.4, 50.7, 60.9, and 76.7 mA/W, respectively. However, for FABr 25, the R-value decreased to 53.9 mA/W. In addition, the D value is an important charact \begin{table}
\begin{tabular}{c c c c} \hline
**Sample Name** & **Resistivity (\(\rho\))** & **Mobility (\(\mu\))** & **Carrier Concentration (n)** \\  & **(\(\Omega\)-cm)** & **(cm\({}^{2}\)/V-s)** & **(\(\times 10^{13}\) cm\({}^{-3}\))** \\ \hline FABr 0 & 0.7604 (0.7704) & 5.23 (5.01) & 2.607 (2.506) \\ \hline FABr 5 & 0.2415 (0.2519) & 11.67 (11.47) & 3.012 (2.821) \\ \hline FABr 10 & 0.2847 (0.2975) & 12.89 (12.64) & 3.841 (3.564) \\ \hline FABr 15 & 0.2198 (0.2249) & 14.61 (14.29) & 5.619 (5.358) \\ \hline FABr 20 & 0.1977 (0.2077) & 26.57 (25.48) & 5.864 (5.469) \\ \hline FABr 25 & 0.8211 (0.8474) & 18.02 (17.48) & 4.782 (4.242) \\ \hline \end{tabular} () is the value after going through the anti-solvent process without adding MACI.  
\end{table} 
Table 1: Resistivity, mobility, and carrier concentration of all the films. the PD area can be detected. Detectivity (D) is related to the R-value and noise of the device and can be validated by these characteristics. The R- and D-values are proportional. As R values are increasing, the D values are also increased. The D values of the produced films increased to 1.82 \(\times\) 1012, 5.12 \(\times\) 1012, 2.61 \(\times\) 1013, 3.07 \(\times\) 1013, and 4.89 \(\times\) 1013 [PERSON] for FABR 0 to FABr 20. However, for FABr 25, it decreased to 2.67 \(\times\) 1013 Jones. The corresponding values are shown in Table 2.  
Figure 7b illustrates the external quantum efficiency (EQE) of the PD as a function of the amount of FABr added. The EQE refers to how much photon is produced compared to injected electrons in the device (PDs) and the value shows the ratio of the number of photons versus electrons. A high EQE indicates a good PD conversion efficiency. With increasing FABr content, the EQE values at 2 V increased to 19%, 28%, 39%, 47%, and 60% for FABr 0 to FABr 20, respectively. However, for FABr 25, the EQE decreased to 42%. Overall, the MAPbI3 perovskite film mixed with MACI shows more improved performance parameters than the previous study. This means that the mixed anionic film has superior photoelectric properties than the single film. Figure 8a shows the ultraviolet (UV) detection performance evaluation of PDs without and with MACI. The response properties of MAPbI3 were measured at a bias voltage of 1 V and a 254 nm light source with a light intensity of 0.774 mW/cm\({}^{2}\).