Carrier Recombination and Diffusion Dynamics in LiBr Passivated CsPbBr_(3) Perovskite Film with Poly(9-vinylcarbazole)Film Underneath  

LiBr钝化CsPbBr_(3)/PVK复合薄膜中载流子复合及扩散动力

作　　者：Jianchang Lv Ao Liu Yan Wan 吕建昌;刘奥;宛岩(北京师范大学化学学院,北京100875)

机构地区：[1]College of Chemistry,Beijing Normal University,Beijing 100875,China

出　　处：《Chinese Journal of Chemical Physics》2025年第1期17-24,I0006-I0018,I0055,共22页化学物理学报(英文)

基　　金：supported by the National Natural Science Foundation of China(No.22273006)。

摘　　要：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.多晶钙钛矿薄膜中的晶界和缺陷的存在会严重影响铯卤化铅钙钛矿器件的性能.LiBr掺杂可以有效钝化CsPbBr_(3)钙钛矿薄膜中的缺陷,但该钝化是否有助于载流子跨晶界传输尚不清楚.本文利用超快.瞬态吸收光谱和瞬态吸收显微镜研究了LiBr钝化前后与聚(9-乙烯基咔唑)薄膜复合的CsPbBr_(3)钙钛矿薄膜中的载流子复合和传输动力学.光致发光成像和瞬态吸收形貌成像表明钝化后的CsPbBr_(3)晶粒明显变大.瞬态吸收光谱和时间分辨光致发光数据表明LiBr钝化能够减慢载流子的双分子复合速率并延长载流子的寿命.钙钛矿层中的光生热空穴会在2ps内转移到聚(9-乙烯基咔唑)层瞬态吸收显微镜测量揭示了LiBr钝化可以促使载流子跨越晶界并扩散到周围的晶粒中.当晶粒间距约为0.9 um时,载流子的扩散时间约为100 ps.

关 键 词：PEROVSKITE Carrier diffusion Transient absorption microscopy 

分 类 号：TB383.2[一般工业技术—材料科学与工程]