Oxide–organic heterostructures: a case study of charge transfer disturbance at a SnO₂–copper phthalocyanine buried interface

Abstract

Reduced tin dioxide/copper phthalocyanine (SnOx/CuPc) heterojunctions recently gained much attention in hybrid electronics due to their defect structure, allowing tuning of the electronic properties at the interface towards particular needs. In this work, we focus on the creation and analysis of the interface between the oxide and organic layer. The inorganic/organic heterojunction was created by depositing CuPc on SnOx layers prepared with the rheotaxial growth and vacuum oxidation (RGVO) method. Exploiting surface sensitive photoelectron spectroscopy techniques, angle dependent X-ray and UV photoelectron spectroscopy (ADXPS and UPS, respectively), supported by semi-empirical simulations, the role of carbon from adventitious organic adsorbates directly at the SnOx/CuPc interface was investigated. The adventitious organic adsorbates were blocking electronic interactions between the environment and surface, hence pinning energy levels. A significant interface dipole of 0.4 eV was detected, compensating for the difference in work functions of the materials in contact, however, without full alignment of the energy levels. From the ADXPS and UPS results, a detailed diagram of the interfacial electronic structure was constructed, giving insight into how to tailor SnOx/CuPc heterojunctions towards specific applications. On the one hand, parasitic surface contamination could be utilized in technology for passivation-like processes. On the other hand, if one needs to keep the oxide's surficial interactions fully accessible, like in the case of stacked electronic systems or gas sensor applications, carbon contamination must be carefully avoided at each processing step.

Understanding Surface Modulation to Improve the Photo/Electrocatalysts for Water Oxidation/Reduction

“…As a result, the interface dipole increases the photovoltage and increases the potential energy of the charge carriers for the surface catalytic reaction. Interestingly, the surface dipole induced by the chemical interaction; in other words, the replacement of hydroxyl groups with electron-withdrawing phosphonate groups strongly affects the surface [95][96][97]. And the phenyl moieties with various substituents change the higher electron-withdrawing abilities also increase the surface generated dipole [98,99] to change the barrier height at the interface (Figure 4b).…”

Незаполненные Электронные Состояния Ультратонких Пленок Тиофен-Фенилен Со-Олигомеров На Поверхности Поликристаллического Золота

“…Авторы предполагают, что наблюдаемые достаточно высокие и различающиеся между собой значения работы выхода пленок СH 3 -PTTP-СH 3 на подложках ex situ Au и in situ Au являются следствием процессов физико-химического взаимодействия на границе пленки и подложек. Среди таких процессов, которые непосредственно влияют на взаимное расположение уровней E vac и E F , часто выделяют пиннинг (pinning) E F [4,35], диффузию молекул из газовой фазы и диффузию атомов металлов в органическую пленку [26,37,38].…”

Незаполненные Электронные Состояния И Потенциальный Барьер В Пленках Замещенных Дифенилфталидов На Поверхности Высокоупорядоченного Пиролитического Графита

“…Раскрытие пятичленного цикла в молекуле фталида требует определенной энергии активации, несколько десятых долей eV [7]. Воздействие на электронную систему тонкой пленки сопряженных молекул можно обеспечить путем переноса электронного заряда на границе органического материала и твердотельной поверхности [8][9][10] или путем введения электроактивных заместителей в молекулу [11,12].…”