https://www.sciencedaily.com/releases/2023/03/230316114032.htm

Organic solar cells are thinner than classic silicon-based cells and they are flexible and probably easier to manufacture. To improve their efficiency, it is important to understand how charges travel through the polymer film. 'These films are made up of an electron donor and an electron acceptor,' explains Elisa Palacino-González, a postdoctoral researcher in the Theory of Condensed Matter group at the Zernike Institute for Advanced Materials, University of Groningen (the Netherlands). 'The charges are delocalized along the entangled polymer chains and transferred from donor to acceptor on a sub-100 femtosecond timescale. So, we need theoretical studies and simulations to understand this process.'

The system that Palacino-González studied is made up of the plastic semiconductor P3HT as the donor and PCBM, a polymer with a C60 'buckyball', as the acceptor. 'We wanted to know how charges are conducted through the material to understand how this material captures and transports energy. For if we understand this, it may be possible to control it.' Experimental studies of the material provide some information, but only on bulk processes. 'Therefore, we combined molecular dynamics simulations to determine the motion of the molecules in the material with quantum chemistry calculations to atomistically model the donor polymer, using time-dependent density functional theory.'