Facile Face-down Annealing Triggered Remarkable Texture Development Of CH₃NH₃PbI₃ Films For High-performance Perovskite Solar Cells

Perovskite solar cells developed from traditional dye sensitized solar cells and became a new type of photovoltaic devices.The name come from the light havest materials CH3NH3PbI3 which have perovskite crystal structure.Since 2009,the development of perovskite solar cells has been accelerated and the power conversion efficient(PCE)has gone beyond 22%.As representative material,CH3NH3PbI3 owns a lot of good photoelectric features,such as direct band gap semiconductor,narrow band gap,high light absorption coefficient,wide spectral absorption range,high carrier mobility and ambipolar charge transport etc.Moreover,due to its cheap raw material and easy to prepare,perovskite has great potential to be commercialization.However,there are still urgent problems to solve,like the further improvement of cell efficiency,cell stability and alleviation of current density-voltage(J-V)hysteresis.One of the most important optimization for perovskite solar cell is CH3NH3PbI3 film.Many researches have been done to prepare high quality CH3NH3PbI3 polycrystalline film.One-step spin-coating method is one of most popular method to prepare CH3NH3PbI3 polycrystalline film,but the film is not good enough.We propose a facile face-down annealing route that can enable the formatiom of(110)textured CH3NH3PbI3 polycrystalline film with large grain size and better crystallinity.By adjusting the temperature in preheating precursor film,the texture degree can be controlled.The perovskite solar cell with textured CH3NH3PbI3 films show improved PCE and better moist resistance.