High Resolution Image Download MS PowerPoint Slide Perovskites (PSKs) show great promise for low-cost X-ray detection. To keep advantages from single crystals and thin-film-based devices, metal-free-mesoporous X-ray detectors (mp-XD) with mp-C/mp-ZrO 2 /mp-TiO 2 /c-TiO 2 /FTO architecture are engineered, integrating PSKs as the last processing step. This reduces complexity and optimizes carrier extraction via distributed interfaces. MP-XDs integrating CsPbI 3 and MAPbI 3 with different bandgaps and operating at zero bias are systematically tested at 8.05 keV with variable high X-ray photon flux, using in operando equipment that links device yield (current–voltage) with material properties (X-ray diffraction (XRD) and photoluminescence (PL)) under a controlled environment. Advanced characterization and modeling demonstrate wide operability for medium/high dose-rate detection (2.4 × 10 2 to 3.1 × 10 5 μGy air s –1 ), applicability up to 50 keV, fast (millisecond) response, and impressive stability. An 18,643 Gy dose is cumulated at 310,000 μGy air s –1 in 17 h without significant device degradation. Self-powered and low-cost mp-XDs hold great promise for FLASH radiotherapy and fusion plasma research.