Temperature-induced structural transition in an organic‐inorganic hybrid layered perovskite (MA)<sub>2</sub>PbI<sub>2‐<i>x</i></sub>Br<sub><i>x</i></sub>(SCN)<sub>2</sub>
Temperature-induced structural transition in an organic‐inorganic hybrid layered perovskite (MA)<sub>2</sub>PbI<sub>2‐<i>x</i></sub>Br<sub><i>x</i></sub>(SCN)<sub>2</sub>
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有机-无机杂化层状钙钛矿 (MA)<sub>2</sub>PbI<sub>2-<i>x</i></sub>Br<sub><i>x 中温度诱导的结构转变</i></sub>(SCN)<sub>2</sub>
DOI：
10.1039/d2ce00733a
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发表时间：
2022
期刊：
影响因子：
3.1
通讯作者：
Yamamoto Takafumi
中科院分区：
文献类型：
--
作者：
Ohmi Takuya;Miura Tomoaki;Shigematsu Kei;Koegel Alexandra A.;Newell Brian S.;Neilson James R.;Ikoma Tadaaki;Azuma Masaki;Yamamoto Takafumi
层状有机-无机杂化卤化物钙钛矿因其优异的性能而成为耐久、可调的光电材料候选材料。在这里，我们报道了层状钙钛矿(MA)2PbI2−xBrx(SCN)2(MA=CH3NH3；0≤x≤1.2)的温度诱导结构转变和光物理性质。同步辐射X射线衍射测量表明，在315K时，(MA)2PbI2(SCN)2(x=0)存在随层间距增加而发生的一级结构相变。我们将这一相变归因于分子离子MA+和SCN−的有序-无序转变。观察到的转变温度随着溴的取代而降低(从320K到270K)，表明分子离子之间的成键作用减弱。BR取代也降低了分解温度，表明层状钙钛矿的热稳定性与层间结合强度有关。(MA)2PbI2(SCN)2的光电流瞬变测量表明，加热后快衰减分量急剧减少，表明结构转变通过分子离子无序产生的钙钛矿层的随机扭曲而减少了晶区中的载流子。这项研究为硫氰酸盐层状钙钛矿族的结构和光物理性质提供了深入的了解。
Layered hybrid organic–inorganic halide perovskites have emerged as durable and tunable candidates for optoelectronic materials due to their outstanding properties. Here, we report the temperature-induced structural transition and photophysical properties of the layered perovskite (MA)2PbI2−xBrx(SCN)2 (MA = CH3NH3; 0 ≤ x ≤ 1.2). Synchrotron X-ray diffraction measurements demonstrate that there is a first-order structural phase transition with an increase of the interlayer distance in (MA)2PbI2(SCN)2 (x = 0) at 315 K. We attribute this transition to order–disorder transformations of the molecular ions, MA+ and SCN−. The observed transition temperature decreases with Br substitution (from 320 K to 270 K), suggesting a weakening of bonding interaction between the molecular ions. A decrease in the decomposition temperature was also observed by Br substitution, indicating that the strength of interlayer bonding is coupled with the thermal stability of the layered perovskite. Photocurrent transient measurements for (MA)2PbI2(SCN)2 reveal a dramatic decrease of the fast decay component upon heating, indicating that the structural transition decreases the carriers in the crystalline domain by random distortion of the perovskite layer derived from disordering of molecular ions. This study provides insight into the structure and photophysical properties of the thiocyanate layered perovskite family.