Minimising recombination losses in novel solar cell materials

Lead Research Organisation: Imperial College London
Department Name: Physics


Semiconductors with ferroelectric (FE) properties are potentially interesting for application to solar cells as they may offer a route to minimise recombination losses. The V-VI-VII materials family (such as SbSI) and halide perovskites are examples of FE materials that also have the benefit of native defects that are benign (i.e. with energies that lie out of the band gap). Both properties suggest these materials could perform well as defect tolerant materials for solar cells. The V-VI-VII family is also interesting because of the tendency to grow in one dimensional, molecular type structures, which could embody interesting new physics as well as an isotropy that could be exploited in devices. However, to date these material systems have hardly been studied in solar cells.
In this project, the student will design an appropriate device model for these ferroelectric semiconductors and use it to relate band structure to the fundamental processes in photovoltaic conversion, to analyse experimental measurements and design test devices. He will characterise materials with a wide range of material and device characterisation tools, including spectroscopic (photoluminescence, Raman, electroluminescence) electrical (transient current and voltage, impedance spectroscopy, current-voltage) and structural analysis techniques, to define material properties. The project takes advantage of a collaboration with physicists at Cardiff University (Profs Emyr Macdonald and Min Gao) who plan to grow such materials and with theorists (Prof Aron Walsh and Dr Jarvist Frost) at Bath who have made preliminary bandstructure calculations. The project will also build on the strong experience of the device physics, materials science and modelling of solar cell materials in EXSS (Nelson, Ekins-Daukes, Barnes), including substantial recent experience with lead halide perovskites.


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Studentship Projects

Project Reference Relationship Related To Start End Student Name
EP/N509486/1 01/10/2016 31/03/2022
2034022 Studentship EP/N509486/1 01/10/2016 31/03/2020 Mohammed Azzouzi
Description The key to efficient performance in optoelectronic devices such as solar cells and light-emitting diodes is to minimize the nonradiative decay of excited states. Such decay occurs when the energy of the excited state is dissipated via the creation of vibrations, i.e., heat in the material. This loss is felt particularly strongly in organic semiconductors and may introduce an intrinsic limitation to the performance of organic light-emitting diodes or solar cells. In this project, we combine experiment and theory to study how charge carriers dissipate energy in organic solar cells, a loss which occurs primarily at the interface between the donor and acceptor molecules. We developed a model for voltage losses in organic solar cells that helps identify new routes for improving organic solar cell performances.
Exploitation Route The model established can be used to explain different trend in voltage losses among series of organic solar cell devices. And ultimately help researchers design molecules with properties that will optimize the power conversion efficiency of organic solar cells and reduce their open circuit voltage losses.
Sectors Electronics,Energy,Environment