Spectral reflectance optimization for planar perovskite solar cells

Abstract

Perovskite solar cells (PSC) have been under development for a few years only, and quickly they have achieved high record efficiencies, above 25 %, attracting great attention as a possible alternative to commercial Si solar cells. However, very few articles have dealt with the optical losses in this type of solar cells, but an important factor to be taken in account for developing highly efficient extra-thin solar cells, such as Perovskite Solar Cells, is the optical reflectance in the solar spectrum for these devices. Then, in this work, we do calculations for planar multilayer perovskite solar cells using the Optical Matrix method for determining the expected reflectance as a function of wavelength, using refraction index and extinction coefficients for each of the materials that typically constitute these solar cells. Our results show that for very thin perovskite absorber layers (less than 350 nm), the optical losses can become very high. Even for a typical perovskite thickness above 450 nm, the total average reflectance in the solar spectrum can be as high as 10 %, approximately.