Electronic structure of hydroxylated La@C82 endohedral metallofullerene: implications on photovoltaic cells

Abstract

ABSTRACT The good performance of a photovoltaic device requires fitting a series of parameters related to electronic structure of materials. Since it is well-known that fullerenol is an excellent electron acceptor with excellent electron conductivity, in this paper we analyse the electronic levels, energy gaps, absorption spectra and electron mobility of hydroxylated La@C (La@C(OH), n = 0−32) endohedral metallofullerene. Furthermore, calculations was performed on one unit of three donor polymers with low energy of the lowest unoccupied molecular orbital and on the well-known acceptor fullerene derivative [6,6]-phenyl-C-butyric acid methyl ester (PCBM) in order to compare the electronic structure and possible donor–acceptor combinations. Interestingly, high coatings have larger energy gap between the highest occupied molecular orbital of donor and the lowest unoccupied molecular orbital of acceptor, which is essential for increasing the open circuit voltage, which relates directly to power conversion efficiency. On the other hand, low coatings have better electron mobility, which is essential in electron transport layers in perovskite-based solar cells. Finally, the absorption spectra of fullerenols were also calculated and compared with the widely used in organic solar cells PCBM, obtaining a broader absorption spectrum in hydroxylated endohedral metallofullerenes helping in the performance of fullerenols for harvesting the solar spectrum.