Feng Yanxing, Chen Quanlin, Yan Xinlong, Fu Xinliang, Wang Di, Ding Zijin, Li Saisai, Geng Cong, Gao Linyue, Zhang Jia, Yang Fan, Qaid Saif M H, Gao Shuyan, Jiang Yuanzhi, Yuan Mingjian
School of Chemistry and Chemical Engineering, School of Materials Science and Engineering, Henan Normal University, 453007, Xinxiang, P. R. China.
State Key Laboratory of Advanced Chemical Power Sources, Key Laboratory of Advanced Energy Materials Chemistry, Ministry of Education), Frontiers Science Center for New Organic Matter, College of Chemistry, Nankai University, 300071, Tianjin, P. R. China.
Angew Chem Int Ed Engl. 2024 Dec 20;63(52):e202412685. doi: 10.1002/anie.202412685. Epub 2024 Nov 5.
Metal halide perovskites are promising candidates for gamma-ray (γ-ray) spectrum detectors. However, achieving high-resolution energy spectra in single-photon pulse-height analysis mode remains challenging, due to the inevitable leakage currents degrade the recognizable fingerprint energies which is critical for resolving γ-ray spectroscopy. We demonstrate under high bias voltage, a deficient contact barrier can lead to excessive surface charge injection, thereby increasing leakage current from electrodes to perovskites. Hence, we conceive to employ surface ligand engineering on perovskite single crystals to manipulate energy levels to suppress leakage current. In particular, anchoring a strong dipole ligand onto the perovskite induced surface charge-density displacement, leading to a downward band bending and heightened the corresponding contact barrier. Consequently, the strategy minimized the detectors' leakage current by an order of magnitude, to as low as 44 nA cm at -100 V. The resulting detectors show a significant improvement in energy resolution, 3.9 % for Na 511 keV γ-rays has been achieved at room temperature. The resulting detector further resolves each fingerprint energy for Eu γ-spectrum, representing one of the best γ-rays perovskite detectors reported to date. Moreover, the detectors exhibited stabilized energy resolution without any degradation under a continuous electric field (1,000 V cm) for over 300 minutes, representing the longest longevity reported to date.
金属卤化物钙钛矿是伽马射线（γ射线）光谱探测器的理想候选材料。然而，在单光子脉冲高度分析模式下实现高分辨率能谱仍具有挑战性，因为不可避免的漏电流会降低可识别的特征能量，而这对于解析γ射线光谱至关重要。我们证明，在高偏置电压下，缺陷接触势垒会导致过多的表面电荷注入，从而增加从电极到钙钛矿的漏电流。因此，我们设想在钙钛矿单晶上采用表面配体工程来调控能级以抑制漏电流。特别是，将强偶极配体锚定在钙钛矿上会引起表面电荷密度位移，导致能带向下弯曲并提高相应的接触势垒。结果，该策略将探测器的漏电流降低了一个数量级，在-100 V时低至44 nA/cm²。所得探测器的能量分辨率有显著提高，在室温下对于Na 511 keV γ射线达到了3.9%。所得探测器进一步解析了Eu γ能谱的每个特征能量，代表了迄今为止报道的最佳γ射线钙钛矿探测器之一。此外，探测器在连续电场（1000 V/cm）下超过300分钟表现出稳定的能量分辨率且无任何退化，代表了迄今为止报道的最长寿命。
