Highly Efficient Perovskite Solar Cells via Nickel Passivation

Abstract

Today's state‐of‐the‐art perovskite solar cells (PSCs) are utilizing polycrystalline perovskite thin films via solution‐processing at low temperature (<150 °C). It is extremely significant to enlarge grain size and passivate trap states for perovskite thin films to achieve high power conversion efficiency. Herein, a strategy for defect passivation of perovskite films via metal ion Ni2+ is for the first time reported. It is found that addition of Ni2+ can significantly generate polyporous PbI2 films due to a different solubility between NiCl2 and PbI2 which benefits penetration of MAI and thus formation of large grain perovskite films eventually. It further demonstrated that Ni2+ ions can effectively passivate PbI3− antisite defects and restrain the generation of Pb0 by interacting with the under‐coordinated halide anions and halide‐rich antisites. Therefore, introducing moderate Ni2+ ions result in a significant increase in photoluminescence lifetime from 285 to 732 ns. Accordingly, a power conversion efficiency of 20.61% can be achieved for the 3% Ni2+ addition‐based PSCs with an enhanced cell stability under ambient conditions. This work provides a promising route toward perovskite films featuring with high crystallinity and low trap‐density.

Controlled n‐Doping in Air‐Stable CsPbI2Br Perovskite Solar Cells with a Record Efficiency of 16.79%

“…When Pb ions (ionic radius of 120 pm) are partially substituted with Ca ions (99 pm), the XRD peaks are expected to have a higher 2 theta angle shift due to shrinkage of the crystal lattice. However, as shown in Figure 1b, the shifts of the (200) peaks are negligible, which is probably due to the minimal doping below the measurement resolution or Ca ions being unincorporated into the crystal lattice 11,24,25. In order to further determine the influence of the CaCl 2 additive contents on the XRD peak position, perovskite films with high concentrations of 3%, 5%, and 10% CaCl 2 additives are prepared.…”

“…Among all the inorganic perovskites, the mixed halide CsPbI 2 Br has attracted intensive attention due to its excellent thermal/light soaking stability and suitable direct bandgap, potentially in the front cell for perovskite‐silicon hybrid tandem applications 7. Numerous studies have been carried out regarding CsPbI 2 Br PSCs 8–12. The highest reported PCE of 16.58% has been achieved by using organic ammoniums to treat the surface of the CsPbI 2 Br film 13…”

Stability Issue of Perovskite Solar Cells under Real‐World Operating Conditions

“…The result could be caused by the stable tetragonal structure of CH 3 NH 3 (Zn:Pb)I 3– x Cl x obtained by compressing the BX 6 octahedron and releasing lattice strain. We also proposed utilization of Ni 2+ ions to passivate a CH 3 NH 3 PbI 3 film and found that Ni 2+ can not only promote the formation of porous PbI 2 film but also passivate PbI 3 − inversion defects . The device's PCE of the MAPbI 3 (Ni 2+ ) increased from 17.25% to 20.6% compared to the device without Ni 2+ .…”

A Review on Additives for Halide Perovskite Solar Cells

“…Ye et al incorporated a novel p‐type conductor Cu(thiourea)I [Cu(Tu)I] in perovskite layer to passivate the trap states of perovskite via interacting with the undercoordinated metal cations and halide anions at the perovskite crystal surface, obtained a breakthrough PCE of 19.9% in inverted PSCs . Gong et al incorporated NiCl 2 to perovskite thin films, and demonstrated that Ni 2+ ions can effectively passivate PbI 3 − antisite defects and restrain the generation of Pb 0 by interacting with the under‐coordinated halide anions and halide‐rich antisites, a PCE of 20.61% was achieved for 3% Ni 2+ addition . Wang et al presented a potassium chloride (KCl) pretreatment method to fabricate high performance PSCs.…”