Maulu Alberto, Navarro-Arenas Juan, Rodríguez-Cantó Pedro J, Sánchez-Royo Juan F, Abargues Rafael, Suárez Isaac, Martínez-Pastor Juan P
UMDO, Instituto de Ciencia de los Materiales, Universidad de Valencia, P.O. Box 22085, 46071 Valencia Spain.
Intenanomat SL, Catedrático José Beltrán 2, 46980 Paterna, Spain.
Nanomaterials (Basel). 2018 Aug 30;8(9):677. doi: 10.3390/nano8090677.
Control of quantum-dot (QD) surface chemistry offers a direct approach for the tuning of charge-carrier dynamics in photoconductors based on strongly coupled QD solids. We investigate the effects of altering the surface chemistry of PbS QDs in such QD solids via ligand exchange using 3-mercaptopropionic acid (MPA) and tetrabutylammonium iodide (TBAI). The roll-to-roll compatible doctor-blade technique was used for the fabrication of the QD solid films as the photoactive component in photoconductors and field-effect phototransistors. The ligand exchange of the QD solid film with MPA yields superior device performance with higher photosensitivity and detectivity, which is due to less dark current and lower noise level as compared to ligand exchange with TBAI. In both cases, the mechanism responsible for photoconductivity is related to trap sensitization of the QD solid, in which traps are responsible of high photoconductive gain values, but slow response times under very low incident optical power (<1 pW). At medium⁻high incident optical powers (>100 pW), where traps are filled, both MPA- and TBAI-treated photodevices exhibit similar behavior, characterized by lower responsivity and faster response time, as limited by the mobility in the QD solid.
控制量子点（QD）表面化学为调节基于强耦合量子点固体的光电导体中的电荷载流子动力学提供了一种直接方法。我们研究了通过使用3-巯基丙酸（MPA）和四丁基碘化铵（TBAI）进行配体交换来改变此类量子点固体中PbS量子点表面化学的影响。采用卷对卷兼容的刮刀技术制备量子点固体薄膜，作为光电导体和场效应光电晶体管中的光活性组件。量子点固体薄膜与MPA进行配体交换可产生具有更高光敏性和探测率的卓越器件性能，这是因为与用TBAI进行配体交换相比，暗电流更小且噪声水平更低。在这两种情况下，负责光电导的机制都与量子点固体的陷阱敏化有关，其中陷阱导致高光导增益值，但在非常低的入射光功率（<1 pW）下响应时间较慢。在中高入射光功率（>100 pW）下，陷阱被填满，经MPA和TBAI处理的光电器件均表现出相似的行为，其特征是响应率较低且响应时间较快，这受限于量子点固体中的迁移率。
