The importance of fixing ion defects in perovskite solar cells in order to make the technology commercially viable is illustrated by the number of research projects with that goal, including new research from the U.K.’s University of Portsmouth as well as two studies published last year from Germany and the U.K.
In the most recent of the three studies, scientists analyzed the effects of transport layers on perovskite solar cell performance, and in particular the anomalous hysteresis in current-voltage curves.
According to their findings, cell design based on adjustment of the properties of the transport layers can be used to make ionic defects move to areas of the perovskite material where they can enhance extraction of electronic charge, thus improving cell performance.
The researchers verified ion migration dynamics in the solar cell may lead to different results, depending on cell design. “In some designs it occurs predominantly within the perovskite while in others it happens at the edges of the perovskite, where it contacts the adjacent materials known as transport layers,” the study stated.
Ion movement affects performance
In steady-state device performance particularly, ion movement is said to play a significant role. As a result, the U.K. researchers concluded the stability of perovskite solar cells may be improved through permittivity – the measure of a material’s ability to store an electric field – and the effective doping density of the transport layers.
“We suggest that the doping density and/or permittivities of each transport layer may be tuned to reduce losses due to interfacial recombination,” state the researchers. “Once this and the rate limiting charge carrier has been identified, our work provides a systematic tool to tune transport layer properties to enhance performance.”
Stability and sensitivity issues have so far prevented commercial uptake of PV technologies based on perovskite.