Technique offers improved resolution and characterization of perovskite-based photovoltaics
Technique offers improved resolution and characterization of perovskite-based photovoltaics lead image
Perovskite-based solar cells are promising alternatives to traditional silicon cells. However, the current research only offers a limited understanding of these complex devices, since the electron transport within the device is physically difficult to probe.
Davenport et al. have adapted a spectroscopic method to capture a “big picture” look at the carrier dynamics within a perovskite-based solar cell. Using cross-correlation current noise spectroscopy, the team measured signals that they could localize to specific locations, including the absorption layer, the transport layer and the interfaces in between, inside the device.
For the study, the authors used a modified form of noise spectroscopy, a method that characterizes the movements of electrons via the fluctuations or noise in an electrical signal. Using this technique, the team measured their device’s current to find signals, such as those coming from electrons at the device’s interfaces, that would normally have been drowned out by much stronger ones. The technique also exhibited spatial selectivity: the resistance measured in one region correlated to the strength of the signal coming from that region. As such, the team could determine the origins of their signals.
Overall, the technique allows researchers to directly and nondestructively probe electron movements throughout a perovskite cell, including its interfaces.
Coauthor Kevin Davenport said the method can complement more traditional techniques, such as impedance spectroscopy, to obtain a more complete understanding of the physical processes occurring within solar cells.
“In a world where we are competing for fractions of a percent in increased efficiency, any additional information is critical,” Davenport said.
Davenport added the authors plan to continue their work in several ways, including testing different perovskites and improving the resolution and range of their technique.
Source: “An analysis of carrier dynamics in methylammonium lead triiodide perovskite solar cells using cross-correlation noise spectroscopy,” by Kevin Davenport, Fei Zhang, Mark Hayward, Logan Joseph Draper, Kai Zhu, and Andrey Rogachev, Applied Physics Letters (2020). The article can be accessed at https://doi.org/10.1063/5.0010260 .
