Electric-Field-Tunable Growth of Organic Semiconductor Crystals on Graphene.

Nguyen, Nguyen Ngan; Lee, Hyo Chan; Kang, Boseok; Jo, Mankyu; Cho, Kilwon · Nano Lett · 2019

basic_science · Level V

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Abstract

Growth of organic semiconductor thin films on a two-dimensional template is affected by its properties and is not well understood. This growth process dictates a thin film's final morphology and crystal structure and is controlled by the interactions between ad-molecules and the template. Here, we report that the template's charge density determines the tuning of such interactions. We observe the dependence of pentacene nucleation on charge carrier density n<sub>g</sub> in graphene under an applied electric field and contact-doping and then deduce that the interaction energy E<sub>A</sub> between the ad-molecule and the graphene is related linearly to n<sub>g</sub>. This tunability of E<sub>A</sub> allows control of the pentacene crystals growth. We exploit these findings to demonstrate that graphene, in which n<sub>g</sub> is controlled, can be used to template pentacene thin films for improved optoelectronic properties, such as electrical conductivity and exciton diffusion length.