Ion‐Bolometric Effect in Grain Boundaries Enabled High Photovoltage Response for NIR to Terahertz Photodetection

Abstract The excellent performance of bolometers in the infrared and terahertz regions has attracted great attention. Understanding the transport process of charged particles is an efficient approach to determine detector performance. However, the lack of studies on the fine‐scale spatial motion of microscopic particles in bolometers has prevented a full understanding of the physical process. Herein, using micro‐nano‐scale optoelectronic performance correlation measurements, it is described how prevalent defect states at the grain boundaries (GBs) decrease current responses. Ions at the GBs of the polycrystalline perovskite bolometer contribute to the photocurrent via thermal excitons. In addition, the built‐in electric field established by ion migration fluctuates periodically with the strength of the light‐heating process due to the interaction between the bolometric effect and the Coulomb force. Additionally, the first ion‐bolometric detector is demonstrated with a significant photovoltage response to infrared and THz waves (75.3 kV W −1 at 1064 nm and 2.3 kV W −1 at 0.22 THz). An examination of the THz images shows the potential for large‐area THz imaging applications. The ion‐bolometric effect combines the broad spectral characteristics of the bolometer effect with the temperature sensitivity due to ion migration and provides a unique perspective on detector technology.