δ‐CsPbI₃ Intermediate Phase Growth Assisted Sequential Deposition Boosts Stable and High‐Efficiency Triple Cation Perovskite Solar Cells

Abstract

Cs/FA/MA triple cation perovskite films have been well developed in the antisolvent dripping method, attributable to its outstanding photovoltaic and stability performances. However, a facile and effective strategy is still lacking for fabricating high‐quality large‐grain triple cation perovskite films via sequential deposition method a, which is one of the key technologies for high efficiency perovskite solar cells. To address this issue, a δ‐CsPbI3 intermediate phase growth (CsPbI3‐IPG) assisted sequential deposition method is demonstrated for the first time. The approach not only achieves incorporation of controllable cesium into (FAPbI3)1–x(MAPbBr3)x perovskite, but also enlarges the perovskite grains, manipulates the crystallization, modulates the bandgap, and improves the stability of final perovskite films. The photovoltaic performances of the devices based on these Cs/FA/MA perovskite films with various amounts of the δ‐CsPbI3 intermediate phase are investigated systematically. Benefiting from moderate cesium incorporation and intermediate phase‐assisted grain growth, the optimized Cs/FA/MA perovskite solar cells exhibit a significantly improved power conversion efficiency and operational stability of unencapsulated devices. This facile strategy provides new insights into the compositional engineering of triple or quadruple cation perovskite materials with enlarged grains and superior stability via a sequential deposition method.

4‐Hydrazinobenzoic‐Acid Antioxidant for High‐Efficiency Sn–Pb Alloyed Perovskite Solar Cells

“…To investigate the long‐term stability of Sn–Pb alloyed PSCs, the integral devices were aged in an N 2 ‐filled glovebox. [ 36 ] As shown in Figure S7b, Supporting Information, the PCE of control PSCs lost more than 20% after aging for 200 h, whereas the devices with HZBA retained more than 90% of their initial PCE during the same time period. These results evidently demonstrated the positive effect of HZBA on improving the stability of Sn–Pb alloyed perovskites.…”

Controlled Crystallization of CsRb‐Based Multi‐Cation Perovskite Using a Blended Sequential Process for High‐Performance Solar Cells

“…In fact, a similar diffraction peak was reported in the literature and it was proposed to come from a δ‐CsPbI 3 phase in the film. [ 20 ] This implies that even such a small amount of Cs + in the PbI 2 layer is sufficient to form trace amounts of CsPbI 3 crystals. Due to the formation of a small amount of δ‐CsPbI 3 crystals, the grain size reduction in PbI 2 layer mixing with Cs + is therefore understandable.…”

“…The δ‐CsPbI 3 phase may act as the nucleation seed in the formation of perovskite crystals. [ 20 ] Interestingly, adding Cs + Rb + ions can reduce the content of δ‐CsPbI 3 , that is, reduce the number of seeds. After the organic salts were spin‐coated on the PbI 2 substrate, they penetrated rapidly into the underlying PbI 2 layer with Cs + Rb + cations, and crystallization began immediately due to the existence of the CsPbI 3 perovskite nuclei.…”

“…It becomes a preferred method for the manufacture of large‐scale devices. [ 19,20 ] However, in the conventional two‐step method, the low solubility of inorganic cesium or rubidium halides in isopropanol (an organic solvent of the precursor in the second step) makes it difficult to incorporate them into the fabrication process and prevents effective intercalation. It has been reported that the diffusion depth of inorganic cations into the PbI 2 lattice is limited in such processes.…”

Growth and Degradation Kinetics of Organic–Inorganic Hybrid Perovskite Films Determined by In Situ Grazing‐Incidence X‐Ray Scattering Techniques

“…[19][20][21] In order to improve the film quality for photovoltaic applications, compositional engineering of perovskites are often done with the change of precursor ratios and the introduction of specific additives. [22][23][24] Currently, there are two main approaches used to fabricate perovskite films including so-called one-step and two-step method. Both methods need to adopt specific deposition techniques like spin coating, blade coating, spray coating and slot-die coating coating.…”