Controlled Crystallization of the Methylammonium Halide Layer in Thin-Film Perovskite Solar Cells

如上所述，为了提高钙钛矿太阳能电池的性能，特别是晶体钙钛矿相的生长需要改进。这是本项目提案的目标。迄今为止，大多数用于制造光伏能量转换的结构薄膜的多孔支架层都是基于相互连接的颗粒状颗粒，这限制了对所生成薄膜孔隙度的控制。在颗粒基薄膜中，种间空隙（孔隙）的大小通常相当小，并且分布广泛。为了增加孔径，必须使用更大的颗粒，这同时降低了效率。因此，有序介孔支架（通过溶胶-凝胶法或纳米浇铸法合成，详见工作计划）在壁厚不变的情况下具有孔隙较大的优点。更大的孔径将允许更大的（但仍然是受限的）钙钛矿晶体与更少的晶界，电荷复合可以发生。因此，该项目的目标是孔径在5nm到100nm之间。这种纳米多孔支架的优点在于孔径分布窄，有利于颗粒基膜的制备。2. 含钙钛矿层的结晶和晶粒尺寸对器件性能的影响均匀的含钙钛矿层的沉积是制备高效、可再生psc的关键挑战之一。纳米多孔支架层（如上所述）有助于更好地控制结晶过程。钙钛矿太阳能电池中的电荷传输和重组澄清钙钛矿太阳能电池中的电荷传输和重组对于开发高效器件至关重要，即通过调整钙钛矿晶体尺寸（见目标2.1）或通过开发和实现新的电荷选择接触。这种对结构薄膜的能级（能带结构）的调整提高了钙钛矿太阳能电池的性能，旨在最大限度地减少接触处的重组并提取电荷。因此，有必要澄清器件内的漂移长度和载流子迁移率。这些参数可以通过线性递增电压（CELIV）测量提取载流子来确定。

To boost the performance of perovskite solar cells, especially the growth of the crystalline perovskite phase needs to be improved, as stated above. This is the objective of this project proposal.1. Scaffold designTo date most of the porous scaffold layers that are used for the fabrication of structured films for photovoltaic energy conversion are based on interconnected, granular particles, which limits the control of the porosity of the generated film. The size of the inter-particular voids (pores) in particle-based films is generally quite small and exhibits a broad distribution. To increase the pore size it is necessary to use larger particles, which at the same time decreases the efficiency. Therefore, ordered mesoporous scaffolds (synthesized by the sol-gel method or by nanocasting, details are stated in the work plan) bear the advantage of larger pores at constant wall thickness. A larger pore size will allow for larger (yet still confined) perovskite crystals with fewer grain boundaries where charge recombination can occur. Therefore the project aims at a pore size between 5 nm and 100 nm. The advantage of such a nanoporous scaffold lies in the narrow distribution of pore sizes, which is advantageous to particle-based films. 2. Influence of the crystallization and crystallite size of the perovskite-containing layer on the performance of the deviceThe deposition of a uniform perovskite-containing layer is one of the key challenges in the preparation of efficient and reproducible PSCs. A nanoporous scaffold layer (as stated above) facilitates better control of the crystallization process.3. Charge transport and recombination in perovskite solar cellsClarifying the charge transport and recombination in perovskite solar cells is of paramount importance in developing efficient devices, i.e. by tuning the perovskite crystal size (see Objective 2.1) or by developing and implementing novel charge-selective contacts. This adjustment of the energy levels (band structure) of the structured films increases the performance of the perovskite solar cells, aiming to minimize the recombination at the contacts and to extract charges. Therefore, it is necessary to clarify the drift length and charge carrier mobility within the device. These parameters can be determined by charge carrier extraction by linearly increasing voltage (CELIV measurements.