Zernike Institute for Advanced Materials, University of Groningen , Nijenborgh 4, Groningen 9747AG, The Netherlands.
Department of Advanced Materials Science, School of Frontier Sciences, University of Tokyo , 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8561, Japan.
ACS Appl Mater Interfaces. 2017 Feb 8;9(5):4719-4724. doi: 10.1021/acsami.6b14934. Epub 2017 Jan 27.
We perform a quantitative analysis of the trap density of states (trap DOS) in PbS quantum dot field-effect transistors (QD-FETs), which utilize several polymer gate insulators with a wide range of dielectric constants. With increasing gate dielectric constant, we observe increasing trap DOS close to the lowest unoccupied molecular orbital (LUMO) of the QDs. In addition, this increase is also consistently followed by broadening of the trap DOS. We rationalize that the increase and broadening of the spectral trap distribution originate from dipolar disorder as well as polaronic interactions, which are appearing at strong dielectric polarization. Interestingly, the increased polaron-induced traps do not show any negative effect on the charge carrier mobility in our QD devices at the highest applied gate voltage, giving the possibility to fabricate efficient low-voltage QD devices without suppressing carrier transport.
我们对 PbS 量子点场效应晶体管 (QD-FET) 中的陷阱态密度 (trap DOS) 进行了定量分析，这些晶体管采用了多种具有宽介电常数范围的聚合物栅介质。随着栅介质常数的增加，我们观察到靠近 QD 最低未占据分子轨道 (LUMO) 的陷阱 DOS 增加。此外，这种增加还伴随着陷阱 DOS 的展宽。我们推断，光谱陷阱分布的增加和展宽源于偶极无序以及极化子相互作用，这些作用出现在强介电极化时。有趣的是，在最高施加栅压下，增加的极化子诱导陷阱对 QD 器件中的电荷载流子迁移率没有任何负面影响，这为制造高效的低电压 QD 器件提供了可能性，而无需抑制载流子输运。
