Improved performance and stability of perovskite solar cells by incorporating gamma-aminobutyric acid in CH3NH3PbI3†
Organic–inorganic hybrid perovskites have attracted enormous attention due to their remarkable properties for high-efficiency solar cells in recent years. However, controlling the morphology of perovskite films is still a challenge using a solution synthesis method. Perovskite films with incomplete coverage are inevitable and this significantly limits the device photoelectric performance and long-term stability. In this work, we have combined gamma-aminobutyric acid iodide (GABAI) and CH3NH3I (MAI) as a mixed amine source in a precursor solution to fabricate a mixed-cation perovskite (GABA)xMA1−xPbI3. As a result, high quality (GABA)xMA1−xPbI3 crystals were synthesized and showed better pore-filling and more complete contact with the TiO2 scaffold, enhancing the power conversion efficiency from 15.08 to 18.31% with respect to the controlled MAPbI3 solar cells. Importantly, the devices that contained GABA+ also showed much higher stability when compared to the reference MAPbI3 devices. This new chemical modification design, using bifunctional mixed cations in organic–inorganic hybrid perovskites, provides an efficient approach for improving both the performance and stability simultaneously.