Presenting a Way to Fabricating High-Efficiency Perovskite Solar Cells
Research results obtained by Professor Noh Jun Hong’s group were published in Joule, an internationally renowned journal.

▲ (From left) Professor Noh Jun Hong (corresponding author) and Ph. D student Jeong Min-Ju (first author)

Professor Noh Jun Hong’s group at the Department of Civil, Environmental, and Architectural Engineering in the College of Engineering successfully developed a high-performance perovskite solar cell* exhibiting an efficiency of over 25% through boosting the radiation of stacked halide perovskite layers.

*A solar cell that employs a halide with a perovskite crystalline structure as a light absorption layer. The perovskite solar cell is drawing considerable attention as a next-generation battery

With the perovskite layer including charge transporting layers stacked therein, the research group demonstrated the importance of the photoluminescence quantum efficiency and its correlation with power conversion efficiency, and presented the way to fabricating high-efficiency perovskite solar cells. The results obtained from the study were published online on November 24 in Joule (impact factor: 46.048), an internationally renowned journal in the field of energy.
- Title of article : Boosting radiation of stacked halide layer for perovskite solar cells with efficiency over 25%
- Authors: Professor Noh Jun Hong (corresponding author, KU) and Ph. D student Jeong Min-Ju (first author, KU)

The research presented a clear correlation between the power conversion efficiency and the photoluminescence quantum efficiency of perovskite solar cells and showed that controlling the interface between the bottom charge transporting layer and the perovskite layer plays an essential role in increasing photoluminescence efficiency. Furthermore, the research group maximized the photoluminescence quantum efficiency by an interface controlling technology that controlled defects in the perovskite films to develop a high-performance perovskite solar cell exhibiting an efficiency of over 25%.

To further approach the theoretical limit of perovskite solar cell efficiency, it is essential to minimize non-radiative recombination (in this process the energy from the recombination of light-induced electrons and holes in a material is not converted into light but lost as heat) due to the defects in a device and maximize radiative recombination (in this process the energy from the recombination is converted into light as photoluminescence), and to understand the suppression mechanism of the non-radiative recombination loss. Photoluminescence quantum efficiency analysis is a useful analytical tool for quantitatively investigating the non-radiative recombination losses occurring in a semiconductor and gaining information about radiative recombination.

Previous studies on photoluminescence quantum efficiency analysis have focused on a single perovskite film rather than a perovskite solar cell device. The photoluminescence quantum efficiency analysis carried out in a perovskite layer with stacked charge transporting layers or in a perovskite device allows for the investigation of not only the characteristics of the perovskite material itself in a device but also the characteristics of the recombination that occurs at the interface of the device. However, there have been few studies on photoluminescence quantum efficiency analysis in a perovskite device.

To search for an effective way of increasing photoluminescence quantum efficiency in a device structure, Professor Noh’s group comparatively analyzed the change in photoluminescence according to the technologies for controlling the interface and defects in the film in a stacked perovskite structure. The results confirmed that non-radiative recombination occurs more at the interface between the bottom charge transporting layer and the perovskite layer than in the perovskite film itself.

The researchers fabricated a perovskite solar cell that exhibited a photoluminescence quantum efficiency of over 25%, demonstrating the importance of analyzing the photoluminescence quantum efficiency in a device structure.

Professor Noh said, “The present study reconfirmed the direction of research to approach the thermodynamic limit, by considering that an excellent solar cell must be an excellent photoluminescence device. Our work is significant in that ae future research directions has been presented for the development of perovskite solar cells, which already have high charge transporting capabilities.”

This work was supported by the Human Resources Program in Energy Technology of the Korea Institute of Energy Technology Evaluation and Planning (KETEP), funded by the Ministry of Trade, Industry and Energy, the Mid-career Research Grant of the National Research Foundation of Korea funded by the Ministry of Science and ICT, and the Phased Carbon Neutral Technology Program.



(Figure 1) A schematic diagram of boosting radiation of full device stack in a perovskite solar cell device.




(Figure 2) (Left) Change of the photoluminescence quantum efficiency in a stacked perovskite structure depending on the control of the bottom interface and the control of the internal defects and (right) change of the photoluminescence quantum efficiency in a perovskite device structure depending on the control of the bottom interface and the control of the internal defects.