Miskin Kumar, Cao Yi, Marland Madaline, Shaikh Farhan, Moore David T, Marohn John A, Clancy Paulette
Department of Materials Science and Engineering, Johns Hopkins University, USA.
Department of Chemical and Biomolecular Engineering, Johns Hopkins University, USA.
Phys Chem Chem Phys. 2025 Jul 23;27(29):15446-15459. doi: 10.1039/d5cp01641j.
Self-regulation of free charge carriers in perovskites Schottky defect formation has been posited as the origin of the well-known defect-tolerance of metal halide perovskite materials. Understanding the mechanisms of self-regulation promises to lead to the fabrication of better performing solar cell materials with higher efficiencies. We investigate many such mechanisms here for CsPbBr, a popular representative of a more commercially viable all-inorganic metal halide perovskite. We investigate different atomic-level mechanisms and pathways of the diffusion and recombination of neutral and charged interstitials and vacancies (Schottky pairs) in CsPbBr. We use nudged elastic band calculations and -derived pseudopotentials within quantum ESPRESSO to determine energies of formation and migration and hence the activation energies for these defects. While halide vacancies are known to exhibit low formation energies, the migration of interstitials is less studied. Our calculations uncover interstitial defect pathways capable of producing an activation energy at, or below, the single experimental value of 0.53 eV observed for the slow, temperature-dependent recovery of light-induced conductivity in bulk CsPbBr. Our work reveals the existence of a low-energy diffusion pathway involving a concerted "domino effect" of interstitials, with the net result that interstitials can diffuse more readily over longer distances than expected. This observation suggests that defect self-healing can be promoted if the "domino effect" strategy can be engaged.
钙钛矿中自由电荷载流子的自调节 肖特基缺陷的形成被认为是金属卤化物钙钛矿材料众所周知的缺陷容忍性的起源。理解自调节机制有望导致制造出性能更好、效率更高的太阳能电池材料。我们在此研究了许多这样的机制，针对CsPbBr，它是一种更具商业可行性的全无机金属卤化物钙钛矿的常见代表。我们研究了CsPbBr中中性和带电间隙原子及空位（肖特基对）扩散和复合的不同原子级机制及途径。我们使用量子ESPRESSO中的推挤弹性带计算和导出的赝势来确定形成能和迁移能，从而确定这些缺陷的活化能。虽然已知卤化物空位具有较低的形成能，但间隙原子的迁移研究较少。我们的计算揭示了间隙缺陷途径能够产生一个活化能，该活化能等于或低于在块状CsPbBr中光致电导率的缓慢温度依赖性恢复所观察到的0.53 eV的单个实验值。我们的工作揭示了存在一种涉及间隙原子协同“多米诺效应”的低能量扩散途径，其最终结果是间隙原子能够比预期更容易地在更长距离上扩散。这一观察结果表明，如果能够采用“多米诺效应”策略，就可以促进缺陷的自我修复。
