1 武汉理工大学材料复合新技术国家重点实验室, 武汉 4300702 先进能源科学与技术广东省实验室佛山分中心佛山仙湖实验室, 广东 佛山 5282163 武汉理工大学材料科学与工程国际化示范学院, 武汉 4300704 郑州大学材料科学与工程学院, 郑州 4500015 Department of Materials Science and Engineering, Graduate School of Semiconductor Materials and Devices Engineering, Perovtronics Research Center, Low Dimensional Carbon Materials Center, Ulsan National Institute of Science and Technology, Ulsan 44919, Republic of Korea
钙钛矿太阳能电池在实现高性能光伏器件方面展现出巨大的商业化应用前景，但面临着一个最主要的挑战是开发工业化规模生产的大面积高质量钙钛矿薄膜制备工艺。在本研究中，为解决大面积印刷难题，通过两步连续刮涂法制备甲脒基钙钛矿吸光层。两步法中第一步沉积的PbI2很容易形成致密的薄膜，这将导致后续沉积的有机胺盐无法和PbI2充分完全反应，在钙钛矿薄膜中残留PbI2，这会严重影响载流子的传输。为了实现理想的多孔PbI2薄膜结构，我们通过在PbI2前驱体溶液中引入四亚甲基亚砜(THTO)。通过形成PbI2·THTO络合物，PbI2的结晶过程被有效控制，易形成片状的PbI2晶粒并沿着垂直基底方向上排列，得到了理想的纳米通道。这为后续的有机胺盐渗入提供了理想的纳米通道。最终5 cm × 5 cm模组实现了18.65%的功率转化效率，并具有出色的存储和热稳定性。这一结果展现了两步连续刮涂法策略在制备大面积钙钛矿太阳能电池方面具备一定的优势。
Solar cells, which are excellent alternatives to traditional fossil fuels, can efficiently convert sunlight into electricity. The intensive development of high-performance photovoltaic materials plays an important role in environmental protection and the utilization of renewable energy. Organic–inorganic hybrid perovskite materials, with a formula of ABX3 (A = methylammonium (MA) or formamidinium (FA); B = Pb or Sn; X = Cl, I, or Br), have exhibited remarkable commercial prospects in high-performance photovoltaic devices owing to their long carrier diffusion length, excellent light absorption properties, high charge carrier mobility, and weak exciton binding energy. Recently, perovskite solar cells, fabricated using halide perovskite materials as light-absorbing layers, have achieved remarkable results; their certified power conversion efficiency has continuously improved and reached 25.7%. However, high-performance devices are usually fabricated using spin-coating methods with active areas below 0.1 cm2. Hence, long-term research goals include achieving a large-scale uniform preparation of high-quality photoactive layers. The current one-step preparation of perovskite films involves the nucleation-crystalline growth process of perovskite. Auxiliary processes, such as using an anti-solvent, are often required to increase the nucleation rate and density of the film, which is not suitable for industrial large-area preparation. Additionally, the large-area preparation of perovskite films by spin-coating will result in different film thicknesses in the center and edge regions of the film due to an uneven centrifugal force. This will cause intense carrier recombination in the thicker area of the film and weak light absorption in the thinner area, which will reduce the performance of the device. To address these problems, the development of a large-area fabrication method for high-performance perovskite light-absorbing layers is essential. In this study, a two-step sequential blade-coating strategy was developed to prepare the FA-based perovskite layer. In general, PbI2 easily forms a dense film; therefore, formamidinium iodide (FAI) cannot deeply penetrate to completely react with PbI2. The PbI2 residue is therefore detrimental to charge transportation. To fabricate the desired porous PbI2 film, tetrahydrothiophene 1-oxide (THTO) was introduced into the PbI2 precursor solution. By forming PbI2·THTO complexes, PbI2 crystallization is controlled, resulting in the formation of vertically packed PbI2 flaky crystals. These crystals provide nanochannels for easy FAI penetration. The 5 cm × 5 cm modules fabricated through this strategy achieved a high efficiency of 18.65% with excellent stability. This indicates that the two-step sequential blade-coating strategy has considerable potential for scaling up the production of perovskite solar cells.
