N-Type Conductive Small Molecule Assisted 23.5 Efficient Inverted Perovskite Solar Cells

摘要

Because of the compatibility with tandem devices and the ability to be manufacturedat low temperatures, inverted perovskite solar cells have generatedfar-ranging interest for potential commercial applications. However, theirefficiency remains inadequate owing to various traps in the perovskite film andthe restricted hole blocking ability of the electron transport layer. Thus, in thiswork, a wide-bandgap n-type semiconductor, 4,6-bis(3,5-di(pyridin-4-yl)phenyl)-2-phenylpyrimidine (B4PyPPM), to modify a perovskite film via an anti-solventmethod is introduced. The nitrogen sites of pyrimidine and pyridine rings inB4PyPPM exhibit strong interactions with the undercoordinated lead ions in theperovskite material. These interactions can reduce the trap state densities andinhibit nonradiative recombination of the perovskite bulk. Moreover, B4PyPPMcan partially aggregate on the perovskite surface, leading to an improvementin the hole-blocking ability at its interface. This modification can also increasethe built-in potential and upshift the Fermi level of the modified perovskitefilm, promoting electron extraction to the electron transport layer. The championdevice achieves a high efficiency of 23.51. Meantime, the sealed deviceretains ≈80 of its initial performance under a maximum power point trackingfor nearly 2400 h, demonstrating an excellent operational stability.