Mimicking Natural Antioxidant Systems for Improved Photostability in Wide-Band-Gap Perovskite Solar Cells

Abstract

Fostered by the top power conversion efficiencies (PCEs) of lab-scale devices, industrialization of perovskite solar cells is underway. Nevertheless, the intrinsically poor stability of these materials still represents a major concern. Herein, inspired by Nature, the use of β-carotene in perovskite solar cells is proposed to mimic its role as a protective pigment, as occurs in natural photosynthesis. Laser-mediated photostability (LMPS) assessment, Fourier-transform infrared spectra analysis acquired in attenuate total reflectance (ATR-FTIR), spectroscopy ellipsometry (SE), and time-resolved photoluminescence (TRPL) measurements under stress conditions prove that the inclusion of a thin β-carotene interlayer promotes a high improvement in the photostability of the perovskite films against photooxidation. Importantly, this is accompanied by an improvement of the solar cell PCE that approaches 20% efficiency with no hysteresis, which is among the highest values reported for a mixed halide (I-Br) perovskite with a band gap of 1.74 eV, relevant for coupling with silicon in tandem cells.

Healing the Buried Interface by a Plant-Derived Green Passivator for Carbon-Based CsPbIBr2 Perovskite Solar Cells

“…The evolution of absorbance spectra illustrates that the homogeneous CsPbIBr 2 perovskite experiences serious phase segregation to I-rich and Br-rich phases under continuous light stimulation; , while the photoinduced phase segregation is suppressed with the smaller absorption variation when introduced to the ET molecule (Figure c,d), illustrating the mitigated halide segregation. In general, V I in the perovskite film acts as media to speed up the phase segregation because of the weaker and longer Pb–I bond than the Pb–Br bond . Due to the strong interaction between the ET molecule and undercoordinated Pb 2+ , the generation of halide vacancy is inhibited, which in turn impedes the halide phase segregation in the perovskite film.…”

Influence of Donor Skeleton on Intramolecular Electron Transfer Amount for Efficient Perovskite Solar Cells

“…The coordination interaction between passivator and PbÀ X framework determines the following propagation of V X defect in final perovskite film. Because the weaker PbÀ I bond than PbÀ Br bond is easily oxidized to I 2 specie, [31] we therefore only calculated the formation energies of V I defects in perovskite films (Figure 2c). The density functional theory (DFT) calculation results show that removing an I atom from CsPbI 2 Br lattice consumes only 1.094 eV, which gradually increases to 1.206-1.932 eV and 1.579-2.393 eV with À NH 2 and À C=O groups as passivation sites for alkyl-, alkenyl-, and benzene-bridging amide molecules, respectively.…”

Influence of Donor Skeleton on Intramolecular Electron Transfer Amount for Efficient Perovskite Solar Cells

“…The coordination interaction between passivator and PbÀ X framework determines the following propagation of V X defect in final perovskite film. Because the weaker PbÀ I bond than PbÀ Br bond is easily oxidized to I 2 specie, [31] we therefore only calculated the formation energies of V I defects in perovskite films (Figure 2c). The density functional theory (DFT) calculation results show that removing Angewandte Chemie an I atom from CsPbI 2 Br lattice consumes only 1.094 eV, which gradually increases to 1.206-1.932 eV and 1.579-2.393 eV with À NH 2 and À C=O groups as passivation sites for alkyl-, alkenyl-, and benzene-bridging amide molecules, respectively.…”