Mengqi Zhang

Bio: Mengqi Zhang is an academic researcher. The author has contributed to research in topics: Fabrication & Perovskite (structure). The author has an hindex of 1, co-authored 1 publications receiving 3 citations.

Controlled crystal orientation of two-dimensional Ruddlesden-Popper halide perovskite films for solar cells

Abstract: Metal halide perovskite solar cells have attracted considerable attention because of their high-power conversion efficiency and cost-effective solution-processable fabrication; however, they exhibit poor structural stability. Two-dimensional (2D) Ruddlesden—Popper (RP) perovskites could address the aforementioned issue and present excellent stability because of their hydrophobic organic spacer cations. However, the crystallographic orientation of 2D crystals should be perpendicular to the bottom substrates for charges to transport fast and be collected in solar cells. Moreover, controlling the crystallographic orientation of the 2D RP perovskites prepared by the solution process is difficult. Herein, we reviewed the progress of recent research regarding 2D RP perovskite films with the focus on the crystallographic orientation mechanism and orientation controlling methods. Furthermore, the current issues and prospects of 2D RP perovskites in the photovoltaic field were discussed to elucidate their development and application in the future.

Effects of the incorporation amount of CdS and Cd(SCN 2 H 4 ) 2 Cl 2 on the performance of perovskite solar cells

Abstract: An excellent organolead halide perovskite film is important for the good performance of perovskite solar cells (PSCs). However, defects in perovskite crystals can affect the photovoltaic properties and stability of solar cells. To solve this problem, this study incorporated a complex of CdS and Cd(SCN 2 H 4 ) 2 Cl 2 into the CH 3 NH 3 PbI 3 active layer. The effects of different doping concentrations of CdS and Cd(SCN 2 H 4 ) 2 Cl 2 on the performance and stability of PSCs were analyzed. Results showed that doping appropriate incorporation concentrations of CdS and Cd(SCN 2 H 4 ) 2 Cl 2 in CH 3 NH 3 PbI 3 can improve the performance of the prepared solar cells. In specific, CdS and Cd(SCN 2 H 4 ) 2 Cl 2 can effectively passivate the defects in perovskite crystals, thereby suppressing the charge recombination in PSCs and promoting the charge extraction at the TiO 2 /perovskite interface. Due to the reduction of perovskite crystal defects and the enhancement of compactness of the CdS:Cd(SCN 2 H 4 ) 2 Cl 2 :CH 3 NH 3 PbI 3 composite film, the stability of PSCs is significantly improved.

Efficient Perovskite Solar Cells Based on Tin Oxide Nanocrystals with Difunctional Modification.

Abstract: Tin oxide (SnO2 ) nanocrystals-based electron transport layer (ETL) has been widely used in perovskite solar cells due to its high charge mobility and suitable energy band alignment with perovskite, but the high surface trap density of SnO2 nanocrystals harms the electron transfer and collection within device. Here, an effective method to achieve a low trap density and high electron mobility ETL based on SnO2 nanocrystals by devising a difunctional additive of potassium trifluoroacetate (KTFA) is proposed. KTFA is added to the SnO2 nanocrystals solution, in which trifluoroacetate ions could effectively passivate the oxygen vacancies (OV ) in SnO2 nanocrystals through binding of TFA- and Sn4+ , thus reducing the traps of SnO2 nanocrystals to boost the electrons collection in the solar cell. Furthermore, the conduction band of SnO2 nanocrystals is shifted up by surface modification to close to that of perovskite, which facilitates electrons transfer because of the decreased energy barrier between ETL and perovskite layer. Benefiting from the decreased trap density and energy barrier, the perovskite solar cells exhibit a power conversion efficiency of 21.73% with negligible hysteresis.