Analysis of Charge Collection Efficiency in Photovoltaic Materials and Devices Using Ion Beam Induced Charge Microscopy

Ion Beam Induced Charge (IBIC) microscopy is a powerful ion beam technique for studying semiconducting materials and devices. This scanning ion microprobe technique mainly utilizing 1-3 MeV energetic hydrogen or helium ions provides a detailed analysis of the electronic characteristics of various semiconducting materials and devices by allowing us to investigate how efficiently they collect charge, at a sub-micro-meter spatial resolution. By measuring the charge pulse heights produced by individual probing ions, IBIC helps in understand how well these devices perform and how reliable they are. The local charge collection efficiency (CCE) fluctuates mainly due to the interplay between how charge carriers diffuse and the surface morphology of the sample. This relationship is crucial for pinpointing the areas within a solar cell that are most vulnerable to radiation-induced damage. In our study, we used IBIC to map out the spatial distribution of CCE to locate electrically active defects in solar cells.<br/>We also looked at how the IBIC signal changes with increasing ion fluence to evaluate the radiation hardness of solar cells. This part of the study is especially important for solar modules used in space, where high levels of radiation can significantly affect their performance and longevity. Our findings show how radiation exposure impacts charge collection efficiency and, in turn, the overall efficiency and durability of the solar cells.<br/>In summary, our research highlights the value of ion beam analysis techniques such as IBIC along with Rutherford Backscattering Spectrometry (RBS) in providing detailed and spatially resolved information about electronic defects, charge collection properties, and elemental migrations in solar cell materials [1,2]. These insights are critical for improving the design and manufacturing of solar cells, especially for applications that need high radiation tolerance, like those used in space.<br/>[1] Mohin Sharma, Mritunjaya Parashar, Darshpreet Kaur Saini, Todd A. Byers, Charles Bowen, Megh N. Khanal, Vincent R. Whiteside, Ahmad R. Kirmani, Joseph M. Luther, Ian R. Sellers, Gary A. Glass, Bibhudutta Rout, " In-situ characterization tools for evaluating radiation tolerance and elemental migration in perovskites," <i>2024 IEEE 52th Photovoltaic Specialists Conference (PVSC)</i>, Seattle, WA, USA, 2024,<br/>[2] Mritunjaya Parashar, Mohin Sharma, Darshpreet Kaur Saini, Todd A. Byers, Joseph M. Luther, Ian R. Sellers, Ahmad R. Kirmani, Bibhudutta Rout,” Probing Elemental Diffusion and Radiation Tolerance of Perovskite Solar Cells via Non-Destructive Rutherford Backscattering Spectrometry”, <i>APL Energy.</i> 2024 March 01; 2(1)