A sn-pb alloy inorganic perovskite film and its application in solar cells

Abstract

The invention belongs to the technical field of perovskite solar cells, and specifically relates to a Sn-Pb inorganic alloy perovskite film and its application in solar cells. The chemical formula of the Sn-Pb inorganic alloy perovskite film is CsSn 1‑x Pb x I 3 , where 0<x<1. The preparation method of the Sn-Pb inorganic alloy perovskite film includes the following steps: combining CsI, SnI 2 ,PbI 2 Dissolved in a solution containing SnF 2 In an organic solvent, stir the reaction for 12-24 hours at 50-80°C, filter to obtain a perovskite precursor solution, spin-coat the perovskite precursor solution on the substrate, and heat at 90-120°C to obtain Sn- Pb inorganic alloy perovskite film.

Description

technical field [0001] The invention belongs to the technical field of perovskite solar cells, in particular to a Sn-Pb alloy inorganic perovskite film and its application in solar cells. Background technique [0002] In recent years, organic-inorganic hybrid halide perovskite materials rely on their unique physical and chemical properties, such as high optical absorption, high carrier mobility, long diffusion length, and simple preparation process, low cost and high efficiency. properties, has received extensive attention in the application field of optoelectronic devices (such as solar cells, LEDs, and photodetectors, etc.). At present, solar cells based on this organic-inorganic hybrid perovskite material have been continuously researched and improved, and their photoelectric conversion efficiency is comparable to that of commercial silicon-based solar cells. However, hybrid perovskite materials usually contain organic cations such as methylammonium (MA + ) and formamid...

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Problems solved by technology

On the one hand, CsPbI 3 It is a black cubic phase at high temperature, but it is easily transformed into a yellow monoclinic phase CsPbI under ambient conditions 3 , thus greatly reducing the photovoltaic performance of the device; on the other hand, the cubic phase of CsPbI 3 The bandgap width is about 1.73eV. As a light-absorbing material, it can only absorb ultraviolet and part of visible light, which will directly reduce the spectral response of solar cells, which is not conducive to the preparation of high-efficiency solar cells in the future.

In this regard, inorganic B-γ-CsSnI without toxic elements 3 The perovskite band gap is about 1.3eV, which can better solve the problem of narrow light absorption range of the material and the problem caused by CsPbI 3 The environmental problems brought by the material lead element, however, CsSnI 3 Divalent tin in the material is easily oxidized to tetravalent tin, which makes its device performance poor

Although all-inorganic perovskite devices have made great progress in terms of stability and photoelectric conversion efficiency under the continuous efforts of researchers, overall, the photoelectric conversion efficiency of inorganic perovskite solar cells is still far behind. It is lower than the organic-inorganic heterojunction perovskite solar cell, among which, a very important reason is that the optical band gap of the inorganic perovskite currently prepared is generally above 1.5eV, which is significantly higher than the optimal band gap of the single-junction solar cell. Gap (1.1-1.4eV)

Previous studies have shown that in organic-inorganic heterojunction perovskite materials, using other metal ions (such as Bi, Sn, etc.) to partially or completely replace Pb in the heterogeneous perovskite can effectively increase light absorption. In inorganic perovskite materials, although some studies have explored ion replacement to reduce the band gap, the band gap is still relatively large.

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