Compositional Engineering for Compact Perovskite Absorber Fabrication Toward Efficient Photovoltaics

The compactness of perovskite active layers plays an essential role in the energy conversion. In order to promote the crystal quality, poly(allylamine hydrochloride) (PAH) was employed as an additive to promote the crystal quality for the active layers. The cationic additive significantly enhanced the compactness of the perovskite absorber film, which promoted the charge transport efficiency, resulting in an average efficiency over 19%. The unique properties of PAH make it act as a 'glue' to link the grain boundaries and promote the crystal quality, thus favoring the charge transfer and suppressing the recombination under the certain doping amount. Meanwhile, the stability of perovskite solar cells in humidity environments was dramatically promoted without encapsulation. The sample has a long shelf life (over 600 h). This strategy can also be used to guide the crystal development of other optoelectronic devices, such as light-emitting diodes and lasers, which have recently involved the hybrid perovskite materials.