Lead‐free A3Bi2I9‐type perovskites are demonstrated as a class of promising semiconductors for high‐performance X‐ray detection due to their high bulk resistivity and strong X‐ray absorption, as well as reduced ion migration. However, due to their long interlamellar distance along their c‐axis, their limited carrier transport along the vertical direction is a bottleneck for their detection sensitivity. Herein, a new A‐site cation of aminoguanidinium (AG) with all‐NH2 terminals is designed to shorten the interlayer spacing by forming more and stronger NH···I hydrogen bonds. The prepared large AG3Bi2I9 single crystals (SCs) render shorter interlamellar distance for a larger mobility‐lifetime product of 7.94 × 10−3 cm2 V−1, which is three times higher than the value measured on the best MA3Bi2I9 SC (2.87 × 10−3 cm2 V−1). Therefore, the X‐ray detectors fabricated on the AG3Bi2I9 SC exhibit high sensitivity of 5791 uC Gy−1 cm−2, a low detection limit of 2.6 nGy s−1, and a short response time of 690 µs, all of which are far better than those of the state‐of‐the‐art MA3Bi2I9 SC detectors. The combination of high sensitivity and high stability enables astonishingly high spatial resolution (8.7 lp mm−1) X‐ray imaging. This work will facilitate the development of low‐cost and high‐performance lead‐free X‐ray detectors.
For the exploration of stable lead-free perovskites for solar cell application, we propose a series of Dion−Jacobson (DJ) double perovskites with formula of BDA2MIMIIIX8 (BDA = 1,4-butanediamine) by substituting two...
The organic-inorganic hybrid halide perovskites have recently attracted enormous interests as photovoltaic materials because of their superior solar cell performance and straightforward fabrication. Unfortunately, the poor stability and the Pb-related...
2D Dion−Jacobson (DJ) perovskites have recently drawn much attention due to their superior charge transport and high environmental stability. Unfortunately, the issue of toxicity regarding the Pb element in perovskites has yet to be solved. Herein, we propose a new BDA 2 CuBiI 8 (1,4-butanediamine) 2D perovskite by substituting two Pb 2+ with the pair of Cu + and Bi 3+ to achieve Pb-free halide perovskites. The first-principles calculations demonstrated the thermodynamic and dynamic stabilities of 2D BDA 2 CuBiI 8 . Furthermore, the results indicate that this new material has a direct band gap of 1.58 eV suitable for solar cells with a theoretical maximal efficiency over 30% and allows direct transitions between band edges contrary to its bulk counterpart. The interlayer interaction of apical I−I is found to play a crucial role in determining the band edges. The findings indicate DJ structure type and double substitution together provide a new method for designing leadfree perovskites for efficient solar cells.
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