Medical X-ray imaging procedures require digital flat detectors operating at low doses to reduce radiation health risks. Solution-processed organic-inorganic hybrid perovskites have characteristics that make them good candidates for the photoconductive layer of such sensitive detectors. However, such detectors have not yet been built on thin-film transistor arrays because it has been difficult to prepare thick perovskite films (more than a few hundred micrometres) over large areas (a detector is typically 50 centimetres by 50 centimetres). We report here an all-solution-based (in contrast to conventional vacuum processing) synthetic route to producing printable polycrystalline perovskites with sharply faceted large grains having morphologies and optoelectronic properties comparable to those of single crystals. High sensitivities of up to 11 microcoulombs per air KERMA of milligray per square centimetre (μC mGy cm) are achieved under irradiation with a 100-kilovolt bremsstrahlung source, which are at least one order of magnitude higher than the sensitivities achieved with currently used amorphous selenium or thallium-doped cesium iodide detectors. We demonstrate X-ray imaging in a conventional thin-film transistor substrate by embedding an 830-micrometre-thick perovskite film and an additional two interlayers of polymer/perovskite composites to provide conformal interfaces between perovskite films and electrodes that control dark currents and temporal charge carrier transportation. Such an all-solution-based perovskite detector could enable low-dose X-ray imaging, and could also be used in photoconductive devices for radiation imaging, sensing and energy harvesting.

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PMMA/Na-MMT nanocomposites were synthesized through a soap-free emulsion polymerization of methyl methacrylate (MMA) using 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS). A conventional anionic surfactant, dodecylbenzenesulfonic acid sodium salt (DBS-Na), was also used to compare with AMPS in the interaction with pristine Na-MMT. Both surfactants were intercalated into the layers of the pristine Na-MMT dispersed in water before polymerization. The nanocomposites with AMPS were exfoliated during polymerization because AMPS made the polymer end-tethered on pristine Na-MMT. The nanocomposites were exfoliated up to the 10 wt % content of pristine Na-MMT relative to the amount of MMA. The molecular weight of PMMA obtained from the nanocomposite with AMPS decreased, and the glass transition temperature (T g) and storage modulus (E‘) of the nanocomposites became higher as the amount of Na-MMT increased.

Solution‐processed zinc oxide nanocrystals (ZnO NCs) hybridized with insulating poly(ethylene glycol) (PEG) are introduced as a cathode interlayer in bulk heterojunction organic photovoltaic cells based on poly(3‐hexylthiophene) (P3HT):(6,6)‐phenyl‐C61 butyric acid methyl ester (PC61BM) blends. The performance of devices with ZnO‐PEG interlayers exhibit an excellent maximum power conversion efficiency (PCE) of 4.4% with a fill factor (FF) of 0.69 under optimized conditions. This enhanced device performance is attributed to decreased series resistance from the hole blocking properties of ZnO, as well as the facilitated electron transport due to the reduced area of ZnO domain boundaries upon addition of PEG. The addition of PEG also lowers the electron affinity of ZnO, which leads to a nearly Ohmic contact at the polymer/metal interface. Moreover, the ZnO‐PEG interlayer serves as an optical spacer that enhances light absorption and thereby increases the photocurrent. The addition of PEG permits control over layer thickness and refractive indices. Improved photon energy absorption is supported by optical simulations. Devices with highly stable metals such as Ag and Au also show dramatically enhanced performance comparable to conventional devices with Al cathode. Due to its simplicity and excellent characteristics, this multifunctional interlayer is suitable for high performance printed photovoltaic cells.