Qiu Chao, Grey John K
Department of Chemistry, University of New Mexico , Albuquerque, New Mexico 87131, United States.
J Phys Chem Lett. 2015 Nov 19;6(22):4560-5. doi: 10.1021/acs.jpclett.5b02168. Epub 2015 Nov 5.
Time-resolved photoluminescence (PL) of isolated methylammonium lead tribromide (MAPbBr3) perovskite crystalline platelets is studied under applied electric fields to understand the influence of ion conformational and translational dynamics on charge recombination dynamics. MAPbBr3 PL decays and intensity transients over ∼100 ps to 10 s time scales show large modulation upon application of electric fields up to ∼ ±10(7) V/m that we attribute primarily to reorientation of the methylammonium cation (MA(+)) dipole moments. On longer time scales, a large fraction of electric field-dependent PL intensity transients exhibit oscillatory behavior and undergo spontaneous switching on time scales comparable to ion drift (∼1-10 s). PL modulation behavior decreases significantly with aging, suggesting diminished reorientational susceptibility (conformational flexibility) of MA(+) groups to applied electric fields.
在施加电场的情况下，对孤立的甲基溴化铅（MAPbBr3）钙钛矿晶体薄片的时间分辨光致发光（PL）进行了研究，以了解离子构象和平动动力学对电荷复合动力学的影响。在高达约±10(7) V/m的电场作用下，MAPbBr3的PL衰减和强度瞬变在约100 ps至10 s的时间尺度上显示出很大的调制，我们主要将其归因于甲基铵阳离子（MA(+)）偶极矩的重新取向。在更长的时间尺度上，很大一部分与电场相关的PL强度瞬变表现出振荡行为，并在与离子漂移相当的时间尺度（约1 - 10 s）上发生自发切换。随着老化，PL调制行为显著降低，这表明MA(+)基团对施加电场的重新取向敏感性（构象灵活性）降低。
