Xie Ziang, Sun Shuren, Yan Yu, Zhang Lili, Hou Ruixiang, Tian Fuyang, Qin G G
State Key Lab for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, People's Republic of China.
J Phys Condens Matter. 2017 Jun 21;29(24):245702. doi: 10.1088/1361-648X/aa6e6c. Epub 2017 Apr 21.
Very recently, the NHCH = NHPbI (FAPbI) perovskite material has attracted considerable attention in fabricating solar cells (SCs). For a photovoltaic material, its refractive index and extinction coefficient, n(λ) and k(λ), as functions of λ, are important to study its optical properties and to estimate the power conversion efficiency potential for the SCs made of it. As far as we know, to date there has been no reports of n(λ) and k(λ) for FAPbI material. In this article, with spectroscopic ellipsometry (SE) measurements, the n(λ) and k(λ), as well as E = 1.45 eV for FAPbI, are acquired. The fast deposition crystallization (FDC) procedure combined with the slowed down annealing (SDA) process is applied to fabricate smooth and uniform FAPbI film on quartz substrate. Several kinds of organic solvents were tried as the second solvent in the FDC procedure, and it is found that when petroleum ether is used, the smallest surface roughness and good FAPbI material purity of the FAPbI film can be acquired. The k(λ) results for FAPbI obtained by SE, calculated from the n(λ) using the Kramers-Kronig relationship, by absorbance, and by first-principles calculations, are compared. The n(λ) and k(λ) for FAPbI are also compared with those for CHNHPbI, GaAs and c-Si.
最近，NHCH = NHPbI（FAPbI）钙钛矿材料在制造太阳能电池（SCs）方面引起了相当大的关注。对于一种光伏材料，其作为波长λ的函数的折射率和消光系数n(λ)和k(λ)，对于研究其光学性质以及估计由其制成的太阳能电池的功率转换效率潜力很重要。据我们所知，迄今为止还没有关于FAPbI材料的n(λ)和k(λ)的报道。在本文中，通过光谱椭偏仪（SE）测量，获得了FAPbI的n(λ)和k(λ)以及E = 1.45 eV。采用快速沉积结晶（FDC）程序与缓速退火（SDA）工艺相结合的方法，在石英衬底上制备出光滑均匀的FAPbI薄膜。在FDC程序中尝试了几种有机溶剂作为第二溶剂，发现当使用石油醚时，可以获得最小的表面粗糙度和良好的FAPbI薄膜材料纯度。比较了通过SE获得的FAPbI的k(λ)结果，该结果是利用Kramers-Kronig关系从n(λ)计算得出的，以及通过吸光度和第一性原理计算得出的结果。还将FAPbI的n(λ)和k(λ)与CHNHPbI、GaAs和c-Si的进行了比较。
