State Key Laboratory of Molecular Reaction Dynamics and Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), Dalian Institute of Chemical Physics, Chinese Academy of Sciences , 457 Zhongshan Road, Dalian, China , 116023.
J Am Chem Soc. 2017 Jan 18;139(2):579-582. doi: 10.1021/jacs.6b10512. Epub 2017 Jan 4.
The excellent charge carrier transportation in organolead halide perovskites is one major contributor to the high performance of many perovskite-based devices. There still exists a possibility for further enhancement of carrier transportation through nanoscale engineering, owing to the versatile wet-chemistry synthesis and processing of perovskites. Here we report the successful synthesis of bromide-gradient CHNHPbBrI single-crystalline nanowires (NWs) by a solid-to-solid ion exchange reaction starting from one end of pure CHNHPbI NWs, which was confirmed by local photoluminescence (PL) and energy dispersive X-ray spectroscopy (EDS) measurements. Due to the built-in halide gradient, the long-distance carrier transportation was driven by the energy funnel, rather than the spontaneous carrier diffusion. Indeed, local PL kinetics demonstrated effective charge carrier transportation only from the high-bandgap bromide-rich region to the low-bandgap iodine-rich region over a few micrometers. Therefore, these halide gradient NWs might find applications in various optoelectronic devices requiring long-distance and directional delivery of excitation energy.
卤化铅钙钛矿优异的载流子输运性能是许多基于钙钛矿的器件具有高性能的主要原因之一。由于钙钛矿具有多功能的湿化学合成和加工特性，通过纳米级工程进一步提高载流子输运性能仍然是有可能的。在这里，我们通过从纯 CHNHPbI NWs 的一端开始的固-固离子交换反应，成功地合成了溴化物梯度 CHNHPbBrI 单晶纳米线 (NWs)，这通过局部光致发光 (PL) 和能量色散 X 射线光谱 (EDS) 测量得到了证实。由于内置的卤化物梯度，长距离载流子输运是由能量漏斗驱动的，而不是自发的载流子扩散。实际上，局部 PL 动力学仅证明了在几微米的距离内，有效电荷载流子从高带隙溴化物富区到低带隙碘化物富区的传输。因此，这些卤化物梯度 NWs 可能在需要远距离和定向传输激发能的各种光电设备中得到应用。
