The low cost and high efficiency of perovskite solar cells are considered to be one of the most promising photovoltaic technologies for low-cost power Generation. Now high-efficiency perovskite batteries are widely used in high-temperature sintering TiO2, limiting its application in flexible devices, and TiO2 under the action of light can be catalyzed decomposition of perovskite, seriously affecting the stability of the Battery.
At present, the efficiency of perovskite battery is more than 23%, and the stability problem has become the biggest bottleneck restricting its tendency to Practicality. Fang Junfeng, researcher of Ningbo Institute of Materials Technology and engineering, cas, conducted in-depth research on the above issues and made new PROGRESS. firstly, in order to solve the problem that TiO2 needs high temperature treatment, It is proposed to use polar fullerene (C60 pyrrolidine tris-acid, CPTA) to replace TiO2 as electronic transmission material, realizing the efficiency ﹥17% of flexible perovskite battery (Adv. Energy Mater. 201 7, 7, 1701144); On this basis, the PbI2 is further introduced into the interface to optimize the growth of perovskite crystals through the interface, which improves the device efficiency to 20.2% (Adv. Funct. Mater. 2018, 28, 1706317). At the same time, in the hole transmission material, through to the polymer electrolyte transmission material to counteract the ion choice (p3ct-n), effectively suppressed the polyelectrolyte the excessive aggregation, thus improved the perovskite thin film on the interface growth, has realized the reverse p-i-n perovskite battery efficiency ﹥19%, The flexible device efficiency also achieves 18%, 1cm*1cm Large area device efficiency ﹥15% (ACS Appl. Mater. Interfaces2017, 9, 31357;
Advanced science, 2018, 1800159). Based on the above-mentioned high-efficiency p-i-n perovskite battery, The team has recently made further progress in the work stability of perovskite batteries. The continuous power output of solar cells in actual power generation (illumination and applied Load) is the core index to measure its Practicability. In the actual work, the ions inside the perovskite film will move along the grain boundary, which is the important reason for the decline of the perovskite battery efficiency. In response to this problem, the team pioneered the strategy of in situ crosslinking to prepare perovskite batteries. A crosslinked liquid organic small molecule (trimethylolpropane triacrylate, tmta, fig. 1a) is introduced into the perovskite film, and the PbI2 chemical ' anchor ' is effectively passivated in the perovskite grain boundary by the TMTA and the Tmta of the grain boundary. To realize the ﹥20% device efficiency; More importantly, after further heating treatment, the TMTA can occur in situ crosslinking (figure 1b), The formation of a stable cross-linked polymer network (fig. 1c), the calcium titanium oxide film ion migration activation energy from 0.21eV to 0.48eV, thereby effectively inhibit the migration of ions along the grain boundary. Based on this strategy, the perovskite battery has a 400-hour continuous maximum power output (load 0.84V) in the Full-spectrum standard sunlight and can still maintain 80% of the initial efficiency (figure 2), and its working stability (T80) has been increased 590 times times compared to the traditional perovskite battery. For the first time, this work realizes the long-term stability of ﹥ 200 hours under the standard sunlight (xe Lamp) and Full Spectrum (non-filter), which provides a new idea and method for the preparation of high efficient and stable perovskite battery. meanwhile, the air stability of perovskite battery (humidity 45%-60%) and thermal stability (85 ℃) is also significantly increased, after ﹥ 1000 hours of aging can still maintain the initial efficiency (or post burn-in Efficiency) more than 90%. Related work to In-situ cross-linking strategy for efficient and operationally stable methylammoniun leads iodide solar cells was published in the nature -communications "(Nature Communications, 2018, 9, 3806).
Fang Junfeng is the only communication author of the paper, and Li Xiaodong is the first Author.
The above work has been supported by the CAS qyzdb-ssw-jsc047, the National Natural Science Foundation of China (51773213, 61474125) and the postdoctoral fund (2017m610380). Fig. 1 (a) Tmta chemical structure; (b) Tmta Heating cross-linking;
(c) Tmta in situ cross-linking of perovskite films