Polarization effects of transition dipoles on photoluminescence and photocurrent in organic-inorganic hybrid perovskites
Polarization effects of transition dipoles on photoluminescence and photocurrent in organic-inorganic hybrid perovskites
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DOI：
10.1016/j.nanoen.2019.104004
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发表时间：
2019-11
期刊：
影响因子：
17.6
通讯作者：
Shengbo Ma;Hengxing Xu;Miaosheng Wang;Jiajun Qin;Ting Wu;Ping Chen;Bin Hu
中科院分区：
文献类型：
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作者：
Shengbo Ma;Hengxing Xu;Miaosheng Wang;Jiajun Qin;Ting Wu;Ping Chen;Bin Hu
由于可移动离子的快速电子极化驰豫和离子极化，钙钛矿基器件中光电行为的极化效应很难解决。本文研究了偏振激发态对MAPbBr3薄膜器件的光致发光和光电流的影响。我们发现，与器件内置场平行和垂直的光学偏振跃迁偶极子产生了显著不同的光致发光和光电流结果。它提供了一种新的理解，即控制磁区几何形状可以进一步提高钙钛矿基应用的发光和光伏性能。结果表明，在MAPbBr3的电子态中，存在光激发跃迁偶极子的各向异性。特别是，这表明在偶极极化区域，光致电子极化可以表现为光致介电极化，这影响了器件的性能。我们还观察到，光激发强度的增加导致场致光致发光猝灭和场致光电流增强都减小，这意味着密度增加的跃迁偶极子之间存在协同作用，有利于发光，但不利于电荷解离。这为有机-无机杂化钙钛矿材料分别在低激发强度和高激发强度下作为高效的光伏和发光材料提供了重要的理解。我们的估算表明，通过控制偶极子取向比，钙钛矿基LED和太阳电池的效率可以分别提高50%和18%。显然，偏振效应为进一步控制钙钛矿光电子学中激发态的偏振来控制光伏和发光行为提供了新的视角。
Polarization effects on optoelectronic behaviors in perovskite-based devices are difficult to address due to quick electronic polarization relaxation and ionic polarization from mobile ions. Here we show the effects of polarized excited states on photoluminescence and photocurrent in MAPbBr3thin-film devices. We found optically polarized transition dipoles, oriented paralleled and perpendicular to device built-in field, give rise to significantly different photoluminescence and photocurrent outcomes. It provides a new understanding that controlling domain geometry can further enhance the light-emitting and photovoltaic performance of perovskite-based applications. The observation proves that the anisotropy of photoexcited transition dipoles is existed in the electronic states of MAPbBr3. Particularly, this indicates that photo-induced electronic polarization can be shown as photoinduced dielectric polarization at the dipolar polarization regime, which impacts device performance. We also observed that increasing photoexcitation intensity leads to a decreases on both field-induced photoluminescence quenching and field-induced photocurrent enhancing, which implies a cooperative interaction between transition dipoles of increased density that favors light emission but infavors charge dissociation. This provides a critical understanding on why organic-inorganic hybrid perovskites can function as efficient photovoltaic and light-emitting materials at low and high excitation intensities, respectively. Our estimation shows that, by manipulating the ratio of dipole orientation, the efficiencies of perovskite-based LEDs and solar cells could be improved by 50% and 18%, respectively. Clearly, the polarization effect presents a new insight on further controlling photovoltaic and light-emitting actions by manipulating the polarization of excited states in perovskite optoelectronics.