Srivastava Priya, Kumar Ramesh, Ronchiya Hemant, Bag Monojit
Advanced Research in Electrochemical Impedance Spectroscopy Laboratory, Indian Institute of Technology Roorkee, Roorkee, 247667, India.
Centre for Nanotechnology, Indian Institute of Technology Roorkee, Roorkee, 247667, India.
Sci Rep. 2022 Aug 20;12(1):14212. doi: 10.1038/s41598-022-16353-6.
The numerous assorted accounts of the fundamental questions of ion migration in hybrid perovskites are making the picture further intricate. The review of photo-induced ion migration using small perturbation frequency domain techniques other than impedance spectroscopy is more crucial now. Herein, we probe into this by investigating perovskite-electrolyte (Pe-E) and polymer-aqueous electrolyte (Po-aqE) interface using intensity modulated photocurrent spectroscopy (IMPS) in addition to photoelectrochemical impedance spectroscopy (PEIS). We reported that the electronic-ionic interaction in hybrid perovskites including the low-frequency ion/charge transfer and recombination kinetics at the interface leads to the spiral feature in IMPS Nyquist plot of perovskite-based devices. This spiral trajectory for the perovskite-electrolyte interface depicts three distinct ion kinetics going on at the different time scales which can be more easily unveiled by IMPS rather than PEIS. Hence, IMPS is a promising alternative to PEIS. We used Peter's method of interpretation of IMPS plot in photoelectrochemistry to estimate charge transfer efficiency [Formula: see text] from the Rate Constant Model. The [Formula: see text] at low-frequency for Pe-E interface exceeds unity due to ion migration induced modified potential across the perovskite active layer. Hence, ion migration and mixed electronic-ionic conductivity of hybrid perovskites are responsible for the extraordinary properties of this material.
关于混合钙钛矿中离子迁移基本问题的众多不同描述，使得情况变得更加复杂。现在，使用除阻抗谱之外的小扰动频域技术对光致离子迁移进行综述更为关键。在此，我们除了采用光电化学阻抗谱（PEIS）之外，还利用强度调制光电流谱（IMPS）研究钙钛矿 - 电解质（Pe - E）和聚合物 - 水性电解质（Po - aqE）界面，以此来探究这一问题。我们报道，混合钙钛矿中的电子 - 离子相互作用，包括界面处的低频离子/电荷转移和复合动力学，导致了基于钙钛矿的器件在IMPS奈奎斯特图中的螺旋特征。钙钛矿 - 电解质界面的这种螺旋轨迹描绘了在不同时间尺度上发生的三种不同的离子动力学，与PEIS相比，IMPS能更轻松地揭示这些动力学。因此，IMPS是PEIS的一种有前景的替代方法。我们采用彼得在光电化学中解释IMPS图的方法，从速率常数模型估计电荷转移效率[公式：见原文]。由于离子迁移在钙钛矿活性层上引起的电位变化改变，Pe - E界面在低频时的[公式：见原文]超过了1。因此，混合钙钛矿的离子迁移和混合电子 - 离子导电性是这种材料具有非凡特性的原因。
