Jeonbuk National University (JBNU) Professor Kim Seong-heon·Professor Jin Kyunghwan(Department of Physics) research team, through collaborative research with Professor Jin-wook Lee's team at Seoul National University, developed a technique that uses electron-beam irradiation to precisely control the work function of perovskite thin films, a next-generation semiconductor material, at the micrometer scale.

This research outcome was published under the title ‘Electron-Beam Enables Spatially Resolved Defect-Mediated Work Function Modulation in FAPbI3 Perovskite Thin Films’ in the latest issue of the international journal 『Advanced Science』 (JCR top 9.4%, Impact Factor 14.1) .

FAPbI3 perovskites are materials that attract attention in various optoelectronic device fields such as next-generation solar cells, photodetectors, and LEDs due to their excellent optical and electrical properties. In particular, to realize highly integrated and high-precision devices, it is important to precisely control the energy levels and electronic states inside the thin film at desired locations.

Previously, chemical doping or thermal treatment have been used to adjust the electrical properties of perovskites, but these methods change the properties of the entire film, making local control at the micrometer scale difficult.

To address this issue, the collaborative research team employed electron-beam irradiation. By adjusting the beam acceleration voltage and exposure time applied to specific regions of the perovskite thin film, they confirmed that iodine-related surface defects formed and that the work function changed continuously and precisely.

The team also elucidated the mechanism by which the iodine vacancy defects formed by electron-beam irradiation act as acceptors (acceptor) and increase the work function. They also succeeded in directly creating a lateral diffusion potential of approximately 0.62 V by selectively irradiating only part of the film with the electron beam, without a separate masking process. Photodetector devices fabricated on this basis exhibited clear rectifying characteristics and effective photogenerated charge separation performance.

This research is significant in that it demonstrated the ability to selectively 'write and modulate' the energy levels on the perovskite surface at desired locations using only electron-beam irradiation, without chemical reagents or complex additional processes. It is expected to be applied to the development of various next-generation devices such as two-dimensional and planar optoelectronic devices, high-performance sensors, and integrated circuits.

Meanwhile, this research was carried out with support from the Ministry of Science and ICT, the Ministry of Education, and the National Research Foundation of Korea.