Investigation of Optical and Dielectric Constants of Organic-Inorganic CH3NH3PbI3 Perovskite Thin Films

Yang A,Zhang W,Bao X,Wang J,Bai M

doi:10.4172/2157-7439.1000407

Abstract

CH3NH3PbI3 thin films with thicknesses in the region of 230-365 nm were prepared. The films were characterized by scanning electron microscope (SEM), x-ray diffraction (XRD), ultraviolet-visible (UV-Vis) absorption and transmittance spectra. Based on the Kramers-Kronig relation and the transmittance spectra, the optical constants of the CH3NH3PbI3 thin films were investigated. Our results show that the absorption coefficient, extinction coefficient, refractive indices, real and imaginary components of the dielectric constant of the CH3NH3PbI3films are basically independent on the thicknesses of the films, which indicate our results are reliable. At 500 nm, above parameters of the films are ~1.38 × 105 cm-1, 0.55, 2.70, 7.01, and 3.13, respectively. The band gap is 1.595 eV. The refractive index of CH3NH3PbI3thin films is 2.84 at 633 nm, which imply that CH3NH3PbI3-based solar cells are ideal antireflection coatings for silicon solar cells (SCs) and are applicable to be top solar cell in monolithic silicon-based tandem solar cells for beyond the efficiency limit of Si SCs. Our results are meaningful for designing optoelectronic devices related to the perovskite thin-films.

Highlights

Organic-inorganic pervoskite of CH3NH3PbX3 (X=Cl, Br, I) families have attracted extreme attention as light-harvesting materials in solar cells (SCs)
The features of the films were characterized by scanning electron microscope (SEM), x-ray diffraction (XRD), UV-Vis absorption and transmittance spectra
Our results show that the band gap of the films, absorption coefficient, extinction coefficient

Summary

Introduction

Organic-inorganic pervoskite of CH3NH3PbX3 (X=Cl, Br, I) families have attracted extreme attention as light-harvesting materials in SCs. Qianqian Lin et al [19] achieved the refractive index and extinction coefficient in the visible to near-infrared wavelength range by a combination of spectroscopic ellipsometry, total transmittance and near-normal incidence reflectance measurements. Chang-Wen Chen et al [20] determined the refractive index and extinction coefficient of CH3NH3PbI3-xClx single sample by using a combination of reflection and transmission ellipsometric measurements, which eliminates the risk of sample to sample variation that could occur in a multi-sample analysis. From the published results about the refractive index and extinction coefficient of CH3NH3PbI3 perovskite films we can see that different research groups obtained different data. Based on the Kramers-Kronig relation [21,22,23] and the transmittance spectra, the optical and dielectric constants of the CH3NH3PbI3 perovskite films were calculated. The change tendency is consistent with the experiment result reported by Philipp LÖper et al [18]

Findings

Calculation and Discussion

Conclusions