HIPERSOL · Modelling of interfaces for high performance solar cell materials

The resistance at the metal contact-semiconductor interface and recombination at the passivating layer-semiconductor interface are two important bottlenecks for improving the performance of current solar cells. These processes are quantum mechanical by nature, but so far most studies and attempts to improve the properties of solar cells have been at the device scale. A main reason for this is the great challenges faced by theoretical modelling. Accurate descriptions of the geometric and electronic structures are required, which necessitate the use of highly sophisticated methodologies based on first principles. At the same time, the interfaces extend in many cases well beyond the size limit of first principles methods, creating the need for more efficient methods, which can operate at larger time and size scales. HiperSol aims to fill this knowledge gap by developing and implementing a multi-scale modelling environment. The physics at the various scales will be treated by a multitude of techniques, and the boundaries between these techniques are of utmost importance for the success of this project. Hence, considerable emphasis will be laid on integrating different methods seamlessly and consistently, with many possibilities to update and improve the different tools. An important development will be the implementation of semi-empirical pseudo-potentials, which can calculate the accurate electronic structure of large structures with up to millions of non-equivalent atoms as well as methods for calculating the lifetime of charge carriers. The multi-scale environment will involve construction of reliable inter-atomic potentials for empirical molecular dynamics, providing input to first principles calculations that in a following stage will be integrated into finite element method (FEM) calculations, reaching the size and time scales of real devices. The modelling will focus on real interfaces and be used to investigate enhancements to present solar cell technology.