English Niall J
School of Chemical and Bioprocess Engineering, University College Dublin, Ireland.
Heliyon. 2020 Mar 12;6(3):e03427. doi: 10.1016/j.heliyon.2020.e03427. eCollection 2020 Mar.
The vibrational density of states (VDOS), electronic structure and optical properties of bulk organo lead-halide perovskites, CHNHPbX (where X = Cl, I and Br), very promising and exciting candidate materials for solar-energy applications, have been studied by means of (hybrid) Density Functional Theory (DFT), with and without spin-orbit coupling, and equilibrium Born-Oppenheimer molecular dynamics (BOMD) in the constant-volume, isothermal (NVT) ensemble at 298 K. Particular emphasis has been directed towards the detailed characterisation of optimal hybrid-DFT strategies to reproduce faithfully the band gap, band structure and optical properties vis-à-vis both experiment and more computationally demanding GW calculations (, those involving the single-particle Green's function, G, and the screened Coulomb interaction, W). The VDOS was found to feature intimate coupling between the lead and halide atoms, and was dominated by acoustic phonon modes - particularly so for chlorine, suggesting this as the more effective candidate material of the considered halides. Bulk optical properties were also determined. In view of promising 'hybrid' architectures of perovskites adsorbed on titania substrates, further simulations of lead iodide in contact with titania have been performed to assess thermal stability, as well as dynamical and structural properties of these systems. It was found that lattice strain led to some atomic layers in perovskite further from the interface adopting less crystal-like structure and less pronounced phonon spectra.
通过（混合）密度泛函理论（DFT），在有和没有自旋轨道耦合的情况下，以及在298K的恒容、等温（NVT）系综中的平衡玻恩 - 奥本海默分子动力学（BOMD），研究了块状有机铅卤化物钙钛矿CHNHPbX（其中X = Cl、I和Br）的振动态密度（VDOS）、电子结构和光学性质，这些材料是太阳能应用中非常有前景且令人兴奋的候选材料。特别强调了对最佳混合DFT策略的详细表征，以便相对于实验和计算要求更高的GW计算（涉及单粒子格林函数G和屏蔽库仑相互作用W的计算）忠实地再现带隙、能带结构和光学性质。发现VDOS的特征是铅和卤原子之间存在紧密耦合，并且主要由声学声子模式主导——对于氯尤其如此，这表明氯是所考虑的卤化物中更有效的候选材料。还确定了块状光学性质。鉴于钙钛矿吸附在二氧化钛衬底上有前景的“混合”结构，已经对碘化铅与二氧化钛接触进行了进一步模拟，以评估这些系统的热稳定性以及动力学和结构性质。发现晶格应变导致钙钛矿中远离界面的一些原子层采用较少的晶体状结构和不太明显的声子谱。
