Researchers from Princeton University have summarized the advancements in using molecular dopants to control the electronic structure of metal halide perovskites. They provide an overview of fundamental work on this doping method for interfaces and adjacent transport layers, which play a predominant role in the design, performance, and stability of perovskite solar cells.
'The development of perovskite technology requires control of the electronic properties, and one of the ways is to dope the material to make it more electron-rich or hole-rich,' said author Antoine Kahn. 'Doping of the bulk of these materials is still in its infancy. It's actually quite difficult to achieve, but a somewhat successful way is to use molecular organic dopants at interfaces.'
Recent progress has focused on the use of external organic dopants to control multiple facets of perovskite cell function, from energy level alignment to the modification of work functions related to electron transport. Molecular dopants have been used to enhance the conductivity of molecular- or polymer-based electron and hole transport layers that often sandwich metal halide perovskite active layers in solar cells.