Enhanced carriers’ separation and transport with ferroelectric polymer P(VDF-TrFE) in hole-transporting material free carbon based perovskite solar cells

Abstract

The separation and transport of carriers is the key to improve the efficiency of the hole transport material free carbon based perovskite solar cells (C-PSCs). Here, ferroelectric polymer P(VDF-TrFE), which is doped into CH3NH3PbI3 layer and inserted as the interface layer between TiO2 and CH3NH3PbI3 layers as well, is adopted to achieve this goal. For one thing, P(VDF-TrFE) improves the crystallinity of perovskite films, leading to lower defects and reducing carriers’ recombination. For the other thing, the built-in field of C-PSCs is enhanced due to the existence of polarized P(VDF-TrFE) when the external voltage is applied to the device, which effectively promotes the transport of carriers at TiO2/CH3NH3PbI3 interface. Finally, a high short-circuit current density of 16.25 mA/cm2 is obtained with a power conversion efficiency of 7.83% for the optimal C-PSCs based on the polarized TiO2/P(VDF-TrFE)/MAPbI3:P(VDF-TrFE). Meanwhile, the hysteresis of the device is reduced as well. This simple and effective method is conducive to the commercialization of C-PSCs in the future.