A radiation detector having a plurality of pixels, comprising: a base substrate ; a thin film transistor on the base substrate ; a scintillator layer on a side of the thin film transistor distal to the base substrate for converting radiation into light; and a photosensor (PS) on a side of the thin film transistor distal to the base substrate and proximal to the scintillator layer for converting light to electrical charges; the photosensor (PS) and the thin film transistor being in two different vertically stacked layers of a vertically stacked multi-layer structure; the photosensor (PS) comprising a photoelectric conversion layer optically coupled to the scintillator layer , wherein the radiation detector further comprises an insulating layer on a side of the photoelectric conversion layer proximal to the thin film transistor ; the photosensor (PS), the thin film transistor , and the insulating layer being in three different vertically stacked layers of the vertically stacked multilayer structure; wherein the photosensor (PS) further comprises a driving electrode and a sensing electrode coupled to the photoelectric conversion layer ; the sensing electrode electrically connected to a drain electrode of the thin film transistor ; and wherein the sensing electrode is on a side of the insulating layer distal to the thin film transistor , characterized in that the driving electrode and the sensing electrode are in a same layer, and the photosensor (PS) further comprises a dielectric layer on a side of the driving electrode and the sensing electrode proximal to the photoelectric conversion layer ; the driving electrode and the sensing electrode have a thickness in the range of 50 nm to 200 nm; the photoelectric conversion layer comprises a perovskite material; and the perovskite material comprises CH 3 NH 3 PbI 3 . a base substrate ; a thin film transistor on the base substrate ; a scintillator layer on a side of the thin film transistor distal to the base substrate for converting radiation into light; and a photosensor (PS) on a side of the thin film transistor distal to the base substrate and proximal to the scintillator layer for converting light to electrical charges; the photosensor (PS) and the thin film transistor being in two different vertically stacked layers of a vertically stacked multi-layer structure; the photosensor (PS) comprising a photoelectric conversion layer optically coupled to the scintillator layer , wherein the radiation detector further comprises an insulating layer on a side of the photoelectric conversion layer proximal to the thin film transistor ; the photosensor (PS), the thin film transistor , and the insulating layer being in three different vertically stacked layers of the vertically stacked multilayer structure; wherein the photosensor (PS) further comprises a driving electrode and a sensing electrode coupled to the photoelectric conversion layer ; the sensing electrode electrically connected to a drain electrode of the thin film transistor ; and wherein the sensing electrode is on a side of the insulating layer distal to the thin film transistor , characterized in that the driving electrode and the sensing electrode are in a same layer, and the photosensor (PS) further comprises a dielectric layer on a side of the driving electrode and the sensing electrode proximal to the photoelectric conversion layer ; the driving electrode and the sensing electrode have a thickness in the range of 50 nm to 200 nm; the photoelectric conversion layer comprises a perovskite material; and the perovskite material comprises CH 3 NH 3 PbI 3 . <EOS>