A large average atomic number, an excellent mobility-charge carrier lifetime, and high sensitivity are intensely required for a semiconductor material to achieve high-performance x-ray detection. Here, we present a new lead-free organic–inorganic hybrid (n-propylammonium)₄SbI₆·I₃ that is designed and constructed with triiodide ions. The incorporated triiodide component can enhance the proportion of large atomic numbers, thereby improving the average atomic number. Semiconductor performance analysis shows that the triiodide-based hybrid exhibits a narrow bandgap of 1.48 eV and a high resistivity (1.07 × 10¹⁰ Ω·cm). Moreover, the wafer-based x-ray detectors exhibit a large mobility-lifetime product of 1.2 × 10⁻³ cm²/V, a high sensitivity of 2.5 × 10³ μC/(Gy_air·cm²), and a low detection limit of 390 nG_yair/s, as well as excellent material and device stability. This work provides new insights to rationally design lead-free hybrid semiconductors for high-performance radiation detectors.

Hole transport material free carbon-based all-inorganic CsPbBr₃ perovskite solar cells (PSCs) are promising for commercialization due to its low-cost, high open-circuit voltage (V_oc) and superior stability. Due to the different solubility of PbBr₂ and CsBr in conventional solvents, CsPbBr₃ films are mainly obtained by multi-step spin-coating through the phase evolution from PbBr₂ to CsPb₂Br₅ and then to CsPbBr₃. The scalable fabrication of high-quality CsPbBr₃ films has been rarely studied. Herein, an inkjet-printing method is developed to prepare high-quality CsPbBr₃ films. The formation of long-range crystalline CsPb₂Br₅ phase can effectively improve phase purity and promote regular crystal stacking of CsPbBr₃. Consequently, the inkjet-printed CsPbBr₃ C-PSCs realized PCEs up to 9.09%, 8.59% and 7.81% with active areas of 0.09, 0.25, and 1 cm², respectively, demonstrating the upscaling potential of our fabrication method and devices. This high performance is mainly ascribed to the high purity, strong crystal orientation, reduced surface roughness and lower trap states density of the as-printed CsPbBr₃ films. This work provides insights into the relationship between the phase evolution mechanisms and crystal growth dynamics of cesium lead bromide halide films.

There have been huge achievements of all-perovskite tandem solar cells, which recently realized the highest power conversion efficiency of 24.8%. However, the complex device structure and complicated manufacture processes severely restrict the further development of all-perovskite tandem solar cells. In this work, we successfully fabricated high-efficiency hole transport material-free (HTM-free) Sn−Pb alloyed narrow bandgap perovskite solar cells (PSCs) by introducing guanidinium thiocyanate (GASCN) and hydroiodic acid (HI) into the perovskite precursor solution. GASCN and HI play a positive synergy effect during perovskite crystallization process resulting in larger grain size, fewer surface defects, and lower trap density to suppress the Sn²⁺ oxidation degradation. Furthermore, they could effectively adjust the energy level of perovskite materials, reduce the energy level difference between perovskite and ITO resulting in more efficiently transport of free hole charge carriers. As a result, with adding GASCN and HI, the achieved highest power conversion efficiency of HTM-free devices increased from 12.58% to 17.85%, which is one of the highest PCEs among all values reported to date for the HTM-free narrow-bandgap (1.2–1.4 eV) Sn−Pb binary PSCs. Moreover, the optimized device shows improved environmental stability. Our additive strategy manifests a remarkable step towards the facile, cost-efficient fabrication of HTM-free perovskite-based tandem solar cells with both high efficiency and simple fabrication process.