Incorporating 4-<i>tert</i>-Butylpyridine in an Antisolvent: A Facile Approach to Obtain Highly Efficient and Stable Perovskite Solar Cells

The synthesis and growth of CH₃NH₃PbI₃ films with controlled nucleation is a key issue for the high efficiency and stability of solar cells. Here, 4-<i>tert</i>-butylpyridine (tBP) was introduced into a CH₃NH₃PbI₃ antisolvent to obtain high quality perovskite layers. In situ optical microscopy and X-ray diffraction patterns were used to prove that tBP significantly suppressed perovskite nucleation by forming an intermediate phase. In addition, a gradient perovskite structure was obtained by this method, which greatly improved the efficiency and stability of perovskites. An effective power conversion efficiency (PCE) of 17.41% was achieved via the tBP treatment, and the high-efficiency device could maintain over 89% of the initial PCE after 30 days at room temperature