前驱体膜处理工艺制备高性能碳基CsPbIBr_(2)钙钛矿太阳能电池

High-performance carbon-based CsPbIBr_(2)perovskite solar cells fabricated by precursor film preparation process

全无机CsPbIBr_(2)钙钛矿材料由于兼顾了光学性能和稳定性而受到人们广泛关注.然而,传统一步旋涂法下制备的CsPbIBr_(2)薄膜通常存在较多缺陷,导致电池器件效率难以提升.考虑到常规反溶剂法工艺窗口较窄且重复性差的问题,提出一种前驱体膜处理工艺以制备高效稳定的碳基CsPbIBr_(2)电池.以异丙醇(IPA)作为反溶剂,通过调控前驱体膜中二甲基亚砜(DMSO)的蒸发速率进而调整钙钛矿的形核位置,并在IPA中加入了硫氰酸胍(C_(2)H_(4)N_(4)S)作为钝化剂来调控钙钛矿的成核及结晶过程.结果表明,优化后的CsPbIBr_(2)薄膜致密性有明显提升,结晶性以及晶粒的取向性有所改善,具有更好的载流子分离和传输效率.制备的电池器件光电转换效率最高达到6.71%,与参比器件5.29%的效率相比提升了近21.16%.此外,经前驱体膜处理工艺后制备的钙钛矿电池具备更高的稳定性.本研究旨在提出一种新的制备技术来提高全DMSO溶剂体系下无机钙钛矿薄膜的质量.

All-inorganic perovskite has attracted extensive attention due to its photovoltaic properties and stability.Typically,the α-phase CsPbI3 has an ideal bandgap of 1.73 eV suitable for the construction of high performance inorganic PSCs.But it suffers phase instability under ambient condition because of the unsatisfactory tolerance factor.By incorporating Br atoms into the perovskite structure,can greatly enhance the phase stability can be greatly enhanced.For example,CsPbBr3 shows an excellent ambient stability and a wide bandgap of 2.3 eV that results in a limited light absorbtion.With the consideration from the unified perspective of the bandgap and the ambient phase stability,CsPbIBr_(2)has a relatively appropriate bandgap(2.05 eV)and higher stability than CsPbI_(3) and CsPbI_(2)Br,which is made a good option for stable and efficient PSCs.However,there exist numerous defects on the CsPbIBr_(2)film prepared by conventional one-step deposition method,which seriously affect the photoelectric conversion efficiency(PCE)of perovskite solar cells(PSCs).Considering the short dripping time and poor reproducibility of conventional anti-solvent technology,a precursor film preparation process is proposed to fabricate efficient and stable carbon-based CsPbIBr_(2)perovskite solar cells.Using isopropyl alcohol(IPA)as the anti-solvent,the nucleation position of perovskite can be adjusted by regulating the evaporation rate of DMSO in the precursor film.In addition,guanidine thiocyanate(C_(2)H_(4)N_(4)S)is added into IPA solution as a passivator to regulate the nucleation and crystallization process of perovskite.The carboxylic acid group of C_(2)H_(4)N_(4)S can crosslink to Pb2+of CsPbIBr_(2)via a chelating interaction,resulting in the easier decomposition of the CsI-DMSO-PbBr_(2)intermediate phase in the spin-coating process of the precursor film.The amino group of C_(2)H_(4)N_(4)S can also promote the crystallization and suppress the ion migration of the perovskite film through hydrogen bonds.The result shows that the compactness of the optimized CsPbIBr_(2)film is significantly improved and the average grain size is about 800nm.The crystallinity and grain orientation are improved,and thus achieving better carrier separation and transport efficiency.The highest PCE of carbon-based CsPbIBr_(2)PSC is obviously improved from 5.29%to 6.71%,i.e.increased by almost 21.16%compared with the control sample.Furthermore,the PSCs with precursor film preparation process possesses better long-term stability.The results obtained in this paper demonstrate that the new preparation technology can improve the quality of inorganic perovskite films in pure DMSO solvent system.