An optimization study on the thickness and measurement conditions of CsPbI₃-based dosimeters in the radiotherapeutic field

CsPbI 3 , a perovskite material, has garnered significant attention in solar cell research owing to its unique crystal structure and optimal band-gap energy. Recently, CsPbI 3 has also been explored for use in dosimeters in the radiotherapeutic field. This study analyzes the reaction characteristics of CsPbI 3 to the 192 Ir radioisotope, focusing on how the material thickness influences performance. The aim of this study is to identify the optimal thickness and measurement conditions of CsPbI 3 . Before fabricating the sensor for evaluation, CsPbI 3 is synthesized using CsI and PbI 2 precursors. Operational voltage factors are determined by analyzing the dark current and photocurrent from four unit-cell sensors with CsPbI 3 thicknesses ranging from 100 to 250 μm. These voltage factors are then applied to evaluate the linearity and repeatability in each sensor. The results of the operational voltage factor tests indicate that +2 V/μm provides optimal electrical stability and measurement efficiency. All sensors demonstrate a high linearity ( R 2 > 0.9990) and satisfy the repeatability criterion (CV < 1.5%), although thicker sensors exhibit higher CV values. Notably, the 250 μm sensor has a margin of error of < 0.1% for repeatability, indicating potential challenges in maintaining performance under varying environmental conditions. Further analysis reveals a positive correlation between sensor thickness and sensitivity. Based on these findings, a +400 V operational voltage is recommended for application to a 200 μm thick sensor as the optimal condition for stable and efficient measurements with CsPbI 3 -based sensors. Future studies involving various radiotherapy equipment and diverse types and energies of radiation are necessary to establish comprehensive optimized conditions for radiotherapeutic quality assurance.