Annealing-Free, High-Performance Perovskite Solar Cells by Controlling Crystallization via Guanidinium Cation Doping

One of the urgent key points to realize the commercialization of perovskite solar cells (PSCs) with robust and excellent performance is the fabrication of high-quality perovskite film. Nevertheless, a traditional thermal annealing (TA) technology is always necessary for a high crystallization perovskite film, and previous reports have suggested that TA could induce heterogeneous nucleation which is inconducive for the formation of smooth and uniform perovskite film, as well as time and cost consuming. Herein, an approach for the annealing-free high-quality perovskite film via the introduction of guanidinium iodine (GAI) is proposed. The organic molecule guanidinium (GA(+)) has a large ionic radius, and this could control the crystallizing rate of annealing-free perovskite film. Ultimately, a perovskite film with larger grain size and lower defect density is acquired through doping 0.10 mol mL(-1) GAI in the precursor solution. Moreover, the fabrication of the electron transfer layer and hole transfer layer is further realized at room temperature. Thus, all room temperature, annealing-free high-performance PSCs are demonstrated. Notably, a GAI-doped device with an outstanding power conversion efficiency (PCE) of 19.25% is obtained, much higher than 16.78% of the pristine device.