Brown Paul A, Kołacz Jakub, Spillmann Christopher M
Center for Bio/Molecular Science and Engineering, United States Naval Research Laboratory, Washington, District of Columbia 20375, United States.
J Phys Chem B. 2024 Apr 11;128(14):3463-3474. doi: 10.1021/acs.jpcb.3c05825. Epub 2024 Mar 27.
The substitution of p-block heteroatoms into polyaromatic hydrocarbons offers the potential for introducing enhanced molecular properties and advancing material development for electro-optical applications. Using density functional theory, we characterize the substitution of boron and nitrogen atoms into a 2,3,6,7,10,11-hexakis(hexathiol)triphenylene (TTP) core, a precursor for a material with a discotic liquid crystal phase, to determine the strength of exciton dissociation and the influence doping has on the formation of a heterojunction with graphene. The substitution of nitrogen and boron into the TTP motif enables tunability of both electron and hole coupling between hetero- and homodyads. The coupling is found to far exceed that of TTP and varied transport behavior with different combinations of doped cores of nitrogen-TTP and boron-TTP is reported. Heterodyads of nitrogen-TTP with boron-TTP appear to be ambipolar in electron/hole coupling, whereas heterodyads of boron- or nitrogen-TTP with TTP form strong electron coupling dyads and homodyads of nitrogen-TTP and boron-TTP form strong hole coupling. Finally, we describe the heterojunction of nitrogen- or boron-TTP with monolayer graphene and observe Ohmic contacts with large hole transport barriers. The presence of induced dipoles occurs at the interface in all heterojunctions, suggesting the possibility of tuning the junction with external potentials and improving exciton dissociation.
将p区杂原子引入多环芳烃中，为引入增强的分子特性和推动电光应用的材料开发提供了潜力。我们使用密度泛函理论，对硼和氮原子取代2,3,6,7,10,11-六（己硫醇）三亚苯基（TTP）核心（一种具有盘状液晶相材料的前体）的情况进行了表征，以确定激子解离的强度以及掺杂对与石墨烯形成异质结的影响。将氮和硼取代到TTP基序中，能够调节异二聚体和同二聚体之间的电子和空穴耦合。发现这种耦合远远超过TTP的耦合，并报道了氮-TTP和硼-TTP掺杂核心的不同组合具有不同的传输行为。氮-TTP与硼-TTP的异二聚体在电子/空穴耦合方面似乎是双极性的，而硼-或氮-TTP与TTP的异二聚体形成强电子耦合二聚体，氮-TTP和硼-TTP的同二聚体形成强空穴耦合。最后，我们描述了氮-或硼-TTP与单层石墨烯的异质结，并观察到具有大空穴传输势垒的欧姆接触。在所有异质结的界面处都存在诱导偶极，这表明有可能通过外部电势调节结并改善激子解离。
