Surface passivation of active layer by introducing sodium alginate for high-performance perovskite photodetectors

Recently, organic metal halide perovskites have attracted wide attention in the field of photovoltaic devices due to series of excellent photoelectric properties. However, the device performance is limited by a large number of surface defects in the perovskite film. Finding an effective method for defect passivation of perovskite film is considered to be a preferred strategy to further improve the performance of perovskite photovoltaic devices. Here, we use an organic metal salt, sodium alginate (SA), to passivate the surface defects of perovskite films to prepare high-performance perovskite photodetectors (PePDs). We find that the introduction of SA can improve the quality of perovskite active layer and passivate the surface defects effectively, which reduce the carrier recombination probability to increase the photocurrent and reduce the dark current of the PePDs. And the detectivity (D*) at 600 nm reaches 3.6×1012 Jones, three times that of the controlled devices. Meanwhile, the PePDs doped with sodium alginate have better stability and device life, which remains 82% of the original performance after being placed in the atmosphere for 7 days. These results indicate that it is an effective strategy to passivate perovskite film with organic metal salt to prepare high-performance PePDs.