论文标题
晶格压缩增加了混合壁性钙钛矿中相分离的激活屏障
Lattice compression increases the activation barrier for phase segregation in mixed-halide perovskites
论文作者
论文摘要
混合卤化物钙钛矿的带隙可调性使它们成为发光二极管和串联太阳能电池的有前途的候选者。然而，照亮混合壁的钙钛矿会导致形成富含单卤化物的隔离相。这种隔离是通过离子迁移发生的，离子迁移也可以在单壁式组成中观察到，因此其控制对于增强寿命和稳定性至关重要。使用依赖压力的瞬态吸收光谱，我们发现MAPB（BRXI1-X）3中碘化物和溴相的富相的形成速率在将压力增加到0.3 GPA时降低了两个数量级。我们从压缩引起的卤化物迁移激活能的增加中解释了这种减少，这是由第一原则计算支持的。通过掺入较小的阳离子来减小晶胞体积减小时，会发生类似的机制。这些发现表明，可以通过压缩应力在物理上或通过组成工程来实现有关卤化物分离的稳定性。
The bandgap tunability of mixed-halide perovskites makes them promising candidates for light emitting diodes and tandem solar cells. However, illuminating mixed-halide perovskites results in the formation of segregated phases enriched in a single-halide. This segregation occurs through ion migration, which is also observed in single-halide compositions, and whose control is thus essential to enhance the lifetime and stability. Using pressure-dependent transient absorption spectroscopy, we find that the formation rates of both iodide- and bromide-rich phases in MAPb(BrxI1-x)3 reduce by two orders of magnitude on increasing the pressure to 0.3 GPa. We explain this reduction from a compression-induced increase of the activation energy for halide migration, which is supported by first-principle calculations. A similar mechanism occurs when the unit cell volume is reduced by incorporating a smaller cation. These findings reveal that stability with respect to halide segregation can be achieved either physically through compressive stress or chemically through compositional engineering.
