Continuous Modification of Perovskite Film by a Eu Complex to Fabricate the Thermal and UV-Light-Stable Solar Cells

Abstract

Perovskite solar cells (PSCs) with simple and low-cost processability have shown promising photovoltaic performances. However, internal defects, external UV light, and heat sensitivity are principal obstacles on their way toward commercialization. Herein, we prepare an Eu complex and directly dope it into the perovskite precursor as a UV filter to decrease the photodegradation of PSCs. The formation of hydrogen bonds between the organic cation of perovskite and the −CF3 in the Eu complex could restrain the escape of organic cations under heating. The Eu complex acts as a redox shuttle to reduce metallic lead (Pb0) and iodine (I0) defects when the PSCs have a long-time operation. Additionally, the ligand-containing aromatic rings could reduce the trace amount of I0 existing as electronic defects in perovskites and together with the long alkyl chain retard the moisture immersion into the PSCs. The best efficiency of PSCs modified by the Eu complex improves up to 20.9%. The excellent thermal stability and UV-light resistance are also realized. This strategy provides a method to design a passivator which continuously modifies the imperfections and inhibits the chemical chain reactions in perovskite film, thereby enhancing the performance and stability of PSCs.

A comparison of molecular iodine evolution on the chemistry of lead and tin perovskites

“…The desirable redox potential of the Eu 2+ /Eu 3 redox couple has since seen the iodide salt (EuI 2 ) replaced in favour of various alternative salts with a range of counter anions. [184][185][186] Nevertheless, the benefits of redox pathways to reduce I 2 have yet to be fully realised. Indeed, several transition and lanthanide metals have suitable redox potentials to encourage redox chemistry between Pb 0 and I 2 as shown in Fig.…”

Enhancing Efficiency and Stability of Perovskite Solar Cells via Photosensitive Molecule-Assisted Defect Passivation

“…To reduce the adverse impact of UV light and prolong the lifetime of perovskite solar cells under sunlight illumination, several efforts have been reported to restrict perovskite degradation. − For instance, Song et al proposed a “sunscreen” strategy that used a tautomeric molecule to realize enhanced UV photostability; 2-hydroxy-4-methoxy­benzophenone was utilized to restrain the degradation of perovskites by the UV tautomeric transition. Consequently, corresponding PSCs exhibited a champion efficiency of up to 23.09% with excellent UV stability .…”