Carbon-based Inorgainc CsPbIBr₂ Perovskite Solar Cells And Optimizing Their Optoelectronic Performance

Perovskite solar cells are a rising star in the photovoltaic field.At present,the efficiency of organic-inorganic perovskite solar cells has reached 25.2%.However,the perovskite layer of organic-inorganic hybird contains volatile and hygroscopic organic cations,which makes its performance particularly unstable.In addition,the most advanced hybrid perovskite solar cells inevitably use expensive and unstable organic hole transport materials and noble-metal electrodes,which undoubtedly puts a heavy economic burden on the commercial deployment of perovskite solar cells.To solve these issues,inorganic cations（such as Cs⁺）can be used to replace organic cations,and cheap,stable and hydrophobic carbon materials can be used to replace the high cost of organic hole transport layer and metal electrode materials.Therefore,this paper mainly use without hole transport layer carbon-based inorganic CsPbIBr₂ perovskite solar cells（PSCs）as the research object.We research three aspects,including:the interface engineering,adding polymer and optimizing temperature.These methods effectively improve the efficiency and stability of the perovskite solar cells,systemic research work is as follows:1.CuSCN is used to modify the interface of CsPbIBr₂ perovskite film.A hydrophobic CuSCN film is introduced into carbon-basedinorganic CsPbIBr₂ PSCsas a multifunctional interlayer between CsPbIBr₂ perovskite film and carbon electrode to improve interfacial energy level alignment and protect CsPbIBr₂ perovskite from ambient moisture.It is found that introducing CuSCN interlayer can not only enhance the hole extraction and suppress the charge recombination in carbon-based CsPbIBr₂ inorganic PSCs,but also improve the stability of the cell.Moreover,the very strong interaction between SCN^-and Pb²⁺remarkably reduce the surface defects of CsPbIBr₂ perovskite film.Consequently,the device with CuSCN interlayer displays an improved power conversion efficiency of 7.30%in comparison with 5.19%for the device without CuSCN interlayer as well as an excellent long-term stability under the ambient condition.2.Cellulose acetate（CA）modified pure CsPbIBr₂ perovskite film.CA can effectly slow down the crystal rate of CsPbIBr₂ film,which obtain less defects,high-quality and smooth-faced perovskite film.CA is added directly to the perovskite precursor solution as an additive,which enhancing the crystallinity and reducing the internal and surface defects ofperovskite film,the film enhances light harvest and suppresses charge recombination so as to improve the performance of carbon-based CsPbIBr₂ perovskite solar cells.With optimizing the weight of CA doped into CsPbIBr₂perovskite precursor solution,the fabricated carbon-base CsPbIBr₂perovskite solar cell achieves an optimized efficiency of7.45%with a fill factor（FF）of 0.64,which is 36.2%higher than its counterpart of without CA.Furthermore,the carbon-based with CA CsPbIBr₂perovskite solar cell shows an excellent long-term stability under either high humidity environment or ambient condition.3.Optimizing the substrate pre-heating and post-annealing temperatures for fabricating high-quality CsPbIBr₂ perovskite films.The optimization of the substrate pre-heating and post-annealing temperatures greatly improves the coverage and crystallinity of CsPbIBr₂perovskite films,leading to enhanced light harvest and suppressed charge recombination.After the device was fabricated,carbon-based CsPbIBr₂ perovskite solar cell exhibits a gratifying conversion efficiency of 8.24%with a high open-circuit voltage of 1.27 V.Moreover,the fabricated carbon-based CsPbIBr₂ perovskite solar cell shows an excellent long-term stability under ambient condition.