The performance of cesium lead halide per-ovskite devices is seriously affected by grain boundaries and other charge traps in the poly-crystalline perovskite thin films.LiBr doping could effectively passivate defects ...The performance of cesium lead halide per-ovskite devices is seriously affected by grain boundaries and other charge traps in the poly-crystalline perovskite thin films.LiBr doping could effectively passivate defects in CsPbBr_(3) perovskite thin films,but it is still unclear that whether the passivation can help the carriers to diffuse across the grain boundaries.Here we have studied the carrier recombina-tion and diffusion dynamics in LiBr passivat-ed CsPbBr_(3) perovskite film with poly(9-vinyl-carbazole)(PVK)film underneath by using ultrafast transient absorption spectroscopy and transient absorption microscopy.The photoluminescence imaging and transient absorption morphological imaging show that LiBr passivating has made the grain size larger and reduced grain boundaries in CsPbBr_(3) film.The transient absorption spectroscopy and time-re-solved photoluminescence data indicate that LiBr passivating has slowed down the bimolecu-lar recombination rate and extended the carrier lifetime.The photoexcited hot holes in the perovskite layer would transfer to the PVK layer in the initial 2 ps.And the transient absorp-tion microscopy measurements reveal that the LiBr passivation can help the carriers to diffuse across the grain boundaries to the surrounding grains in the CsPbBr_(3) perovskite films.The carrier diffusion time is around 100 ps when the distance between two grains is~0.9μm.展开更多
基金supported by the National Natural Science Foundation of China(No.22273006)。
文摘The performance of cesium lead halide per-ovskite devices is seriously affected by grain boundaries and other charge traps in the poly-crystalline perovskite thin films.LiBr doping could effectively passivate defects in CsPbBr_(3) perovskite thin films,but it is still unclear that whether the passivation can help the carriers to diffuse across the grain boundaries.Here we have studied the carrier recombina-tion and diffusion dynamics in LiBr passivat-ed CsPbBr_(3) perovskite film with poly(9-vinyl-carbazole)(PVK)film underneath by using ultrafast transient absorption spectroscopy and transient absorption microscopy.The photoluminescence imaging and transient absorption morphological imaging show that LiBr passivating has made the grain size larger and reduced grain boundaries in CsPbBr_(3) film.The transient absorption spectroscopy and time-re-solved photoluminescence data indicate that LiBr passivating has slowed down the bimolecu-lar recombination rate and extended the carrier lifetime.The photoexcited hot holes in the perovskite layer would transfer to the PVK layer in the initial 2 ps.And the transient absorp-tion microscopy measurements reveal that the LiBr passivation can help the carriers to diffuse across the grain boundaries to the surrounding grains in the CsPbBr_(3) perovskite films.The carrier diffusion time is around 100 ps when the distance between two grains is~0.9μm.
