Perovskite solar cell materials and particularly the champion CH3NH3PbI3 has attracted a decent attention among the researchers and introduced as 'Next big thing in photovoltaics'. This 4-year young technology now can compete with 40 years old technology of silicon and CIGS solar cells in the terms of efficiency. Recently a mixed composition of different cation and halogens together with lead has been introduced that holds the world record efficiency and best reported stability so far.
In our previous projects Snic2014-3-17, 2015-6-65, 2016-5-5-7 and a part of large project Snic2016-10-23 , we have investigated the cation exchange, vacancy movement , TDDFT of charge density response and Stark effect in these materials. In continuation of previous projects and based on our recent publications (ACS Nano 2017-DOI: 10.1021/acsnano.6b07916 and Energy and Environmental Science DOI: 10.1039/C6EE00030D) , here in this proposal i would tackle the chemical bonding roles and ionic movement in the mixed compositon perovskite materials. The calculations covers the phonon dispesion, time dependent DFT , Nudge elastic bond as well as typical ground state DFT calculation of the materials with mixed structure(For example MAxFAyCs(1-x-y)PbIzBr(1-z)) in which a combinations of cations and anions implemented in the perovskite structure.
The new mixed phase compounds are in a large extent unknown and the results of this project based on our fundamental approach would be of crucial importance for the research field. Moreover, The results wold be coupled to the experimental measurements in a joint theoretical-experimental work.