CsPbI3 perovskite has drawn much attention due to its thermal stability and outstanding photovoltaic performance with suitable band gap (~1.73 eV) and high absorption coefficient.
Nonradiative recombination is mainly governed by undesirable energy levels at the interface between perovskite film and the charge transport layers. Therefore, it's important to modify the heterojunction interface with the desired energy level alignment for highly efficient and stable CsPbI3 perovskite solar cells (PSCs).
Recently, a research group led by Prof. LIU Shengzhong from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences developed a beach-chair-shaped band structure (CSB) for CsPbI3 perovskite solar cells with stabilized efficiency as high as 17.12% and Voc up to 1.15V. The bare PSCs without any encapsulation retained 90.4% of their initial cell efficiency after being stored for one month under ambient conditions.
This work was published in Cell Reports Physical Science on Sept. 2.
Schematic structure of the optimized beach-chair-shaped band (CSB) device (Image by WANG Kang)
"The CSB architecture demonstrates an enhancement in the energy level match of CsPbI3 at the CsPbI3/PTAA(TiO2) interface, improving carrier transport at each interface, which is the main advantage of this designed structure. Another advantage is the effective reduction of defect density and interfacial recombination loss at the modified interface," said Prof. LIU.
The optimized CSB structure could further improve the stability of the β-CsPbI3 layer as well as the entire device by organic PMA cation surface passivation, gradient Br doping, and CsPbI3 QD capping.
This work provides a promising strategy to further improve the performance of Cs-based halide perovskites through an approach also applicable to other optoelectronic devices and perovskite material systems.
This work was supported by the National Natural Science Foundation of China, Joint Talent Cultivation Funds of NSFC-HN, National Key Research and Development Program of China, and DNL Cooperation Fund CAS. (Text by WANG Kang)