钙钛矿太阳能电池近年来发展十分迅速，具有光电转化效率高、制备过程温度低并且能耗小等优点，在降低环境污染，解决能源危机方面具有十分可期的应用前景。光生空穴的抽取与传输对钙钛矿电池的性能起决定性作用。然而由于钙钛矿薄膜表面缺陷态的存在以及现有空穴传输材料的性能不足限制了器件性能的进一步突破。因此，本论文从钙钛矿/空穴传输层界面处理、新型空穴传输材料的设计开发、优化无掺杂空穴传输层制备工艺等方面展开研究，具体的研究内容如下：首先设计合成了一种新型的多功能缺陷钝化材料2-三氟甲基苯乙胺氢碘酸盐（2-CF3-PEAI），对钙钛矿/空穴传输层界面进行处理，有效的抑制了钙钛矿表面深能级缺陷单质铅Pb0的生成，2-CF3-PEAI与碘化铅反应生成一层疏水二维钙钛矿薄膜，有利于抑制离子在器件内部的扩散，提升器件的稳定性。三氟甲基可以通过氢键、离子键等作用力对薄膜表面的不同缺陷进行抑制，降低载流子的复合。针对常用spiro-OMeTAD分子存在的不足，设计合成了两种含硫原子的新型空穴传输材料T1和T2。硫原子的引入有效的降低了材料的价带位置，提高了材料的电学性能。通过硫原子与钙钛矿表面Pb原子之间的相互作用，钝化未配位Pb2+离子，降低缺陷态密度从而提高器件的性能。通过硫原子与金属背电极之间的强相互作用，有效的抑制了离子在器件内部的扩散，从而提升了器件的稳定性。使用T2材料，1 cm2的电池取得了24.0%的认证效率。材料的低成本和高性能使其在工业化的应用成为可能。设计合成了一类新型的含三苯胺的吡咯基空穴传输材料T3，具有合成路线简单、反应的产率高、综合成本低和带隙可调等优点。通过改变最后一步的反应原料可以实现对空穴传输材料性能的调控。基于含有氟原子的T3-F材料，器件取得了接近25%的光电转化效率（0.1 cm2）。在MPPT测试中，电池连续工作1350 h后，仍能维持初始效率的80%左右。通过溶剂的对比，选择含氯的脂肪烃溶剂并结合紫外光后处理手段，有效的氧化了spiro-OMeTAD，提高材料的导电性，无掺杂条件下实现了20%的光电转化效率。对比发现使用低沸点溶剂有利于提高spiro-OMeTAD薄膜的结晶性，有利于空穴在分子间的传输。
Perovskite solar cells have developed rapidly in recent years and it has advantages of excellent power conversion efficiency, low temperature and low energy consumption in the preparation process. It has a promising application prospect in reducing environmental pollution and solving energy crisis. The extraction and transport of photogenerated holes play a decisive role in the performance of perovskite solar cells. However, the defects at the interface between perovskite film and hole transport layer, and the imperfect properties of commonly used hole transport materials limit the device performance. Herein, in this thesis, perovskite surface post-treatment was studied, new hole transport materials were designed and synthesized, hole transport layer preparation process was optimized, the specific research contents are as follows:Firstly, a new multifunctional perovskite surface post-treatment material, 2- trifluoromethyl phenethylamine hydroiodide (2-CF3-PEAI), was designed and synthesized. After simple surface post-treatment, the formation of metallic Pb0, a deep level defect on the perovskite surface, was effectively inhibited, and a hydrophobic two-dimensional perovskite film was spontaneously formed which is conducive to inhibiting the diffusion of ions in the device and improving the stability of the device. Trifluoromethyl can deactivate different type defects on the film surface by hydrogen bond and ionic bond, and thus reduce carrier recombinationTo solve the shortage of spiro-OMeTAD, two novel hole transport materials T1 and T2 containing sulfur atoms were designed and synthesized. The introduction of sulfur effectively reduces the valence band energy level and improves the hole mobility and conductivity of the hole transport materials. Through the interaction between S atoms and Pb atoms, the uncoordinated Pb2+ ions on the perovskite surface were passivated, and the defect density was reduced which enhanced the performance of the perovskite devices. Through the strong interaction between sulfur atoms and back electrodes, the diffusion of ions in the device is effectively inhibited, thus improving the stability of the device. A certified efficiency of 24.0% was achieved with an area of 1 cm2 based on T2. The low-cost and high-performance of the new material provide the opportunity of industrial application.A class of pyrrole-based hole transport materials T3 containing triphenylamine was designed and synthesized, which has the advantages of simple synthesis route, high yield, low cost and adjustable band gap. The properties of hole transport materials can be adjusted by using different materials in the last step. Based on fluorine atoms containing T3-F material, the device achieved a power conversion efficiency of nearly 25% (0.1 cm2), and in the MPPT test, perovskite solar cell maintained 80% of its initial efficiency after 1350 hours continuous light illumination.Through the comparison of solvents, spiro-OMeTAD can be effectively oxidized using the chlorinated aliphatic hydrocarbon solvent combining with the UV post-treatment method, which enhances the conductivity, and a 20% power conversion efficiency was achieved using spiro-OMeTAD as hole transport material without doping. It is also found that the use of low boiling point solvent is conducive to improving the crystallinity of the spiro-OMeTAD film which facilitates the transport of holes between molecules.
