Shadow‐Free Back‐Contact Perovskite Thin‐Film Detectors for Direct Extreme‐Ultraviolet and Soft X‐Ray Sensing

ABSTRACT

Extreme ultraviolet (EUV) and soft x‐ray detection is of paramount importance for synchrotron radiation, advanced lithography, and astrophysics. However, conventional semiconductor detectors often suffer from electrode shadowing and significant parasitic absorption in the low‐energy regime (0.1–2 keV). Here, we report a high‐performance EUV and soft x‐ray detector based on a triple‐cation perovskite (TC‐PVK) Cs _0.05 (FA _0.83 MA _0.17 ) _0.95 Pb(I _0.83 Br _0.17 ) ₃ incorporating a quasi‐interdigitated back‐contact (QIBC) planar device architecture. Unlike traditional vertical geometries, the QIBC design improves charge extraction and reduces the shielding effect from the metal electrodes, thus improving the uniform collection and flux‐to‐current linearity. The TC‐PVK detector takes advantages of high attenuation efficiency, achieving a high sensitivity of 2.3 × 10 ⁴ µC Gy _vac ⁻¹ cm ⁻² under synchrotron EUV radiation (100 eV) in high vacuum condition, which enables reliable quantification of photon flux within selected low‐energy x‐ray windows. Spatially resolved photoluminescence and photocurrent mapping reveal efficient and balanced charge extraction at the perovskite/transport‐layer interfaces, facilitating a relatively rapid temporal response. This work not only highlights the superior x‐ray stopping power of TC‐PVK but also underscores the pivotal role of back‐contact engineering in unlocking the full potential of perovskite‐based sensors for next‐generation soft x‐ray spectroscopy and imaging.