Hybrid organic–inorganic perovskites, MAPbX₃ (X = halogen), containing methylammonium (MA: CH₃–NH₃⁺) in the large voids conformed by the PbX₆ octahedral network, are the active absorption materials in the new generation of solar cells. CH₃NH₃PbBr₃ is a promising member with a large band gap that gives rise to a high open circuit voltage. A deep knowledge of the crystal structure and, in particular, the MA conformation inside the perovskite cage across the phase transitions undergone below room temperature, seems essential to establish structure–property correlations that may drive to further improvements. The presence of protons requires the use of neutrons, combined with synchrotron XRD data that help to depict subtle symmetry changes undergone upon cooling. We present a consistent picture of the structural features of this fascinating material, in complement with photocurrent measurements from a photodetector device, demonstrating the potential of MAPbBr₃ in optoelectronics.

中文翻译：

---

阐明MAPbBr ₃钙钛矿中的甲基铵（MA）构型及其在太阳能电池中的应用

杂化的有机-无机钙钛矿，MAPbX ₃（X =卤素），在由PbX ₆八面体网络形成的大空隙中含有甲基铵（MA：CH ₃ -NH ₃ ⁺），是新一代太阳能电池中的活性吸收材料。 。CH ₃ NH ₃ PbBr ₃是一个有前途的成员，带隙大，会产生高的开路电压。对晶体结构的深入了解，尤其是钙钛矿笼子内部在低于室温下发生的相变中的MA构象的知识，对于建立可能促进进一步改进的结构与特性的关联似乎至关重要。质子的存在需要使用中子，再加上同步加速器XRD数据，该数据有助于描述冷却时发生的细微对称性变化。我们提供了这种引人入胜的材料的结构特征的一致图片，以及来自光电探测器设备的光电流测量结果，证明了MAPbBr ₃在光电子学中的潜力。