Heterostructures Of Organic Semiconductors Research Articles

Optical signatures of Förster-induced energy transfer in organic/TMD heterostructures

Hybrid van der Waals heterostructures of organic semiconductors and transition metal dichalcogenides (TMDs) are promising candidates for various optoelectronic devices, such as solar cells and biosensors. Energy-transfer processes in these materials are crucial for the efficiency of such devices, yet they are poorly understood. In this work, we develop a fully microscopic theory describing the effect of the Förster interaction on exciton dynamics and optics in a WSe2/tetracene heterostack. We demonstrate that the differential absorption and time-resolved photoluminescence can be used to track the real-time evolution of excitons. We predict a strongly unidirectional energy transfer from the organic to the TMD layer. Furthermore, we explore the role temperature has in activating the Förster transfer and find a good agreement to previous experiments. Our results provide a blueprint to tune the light-harvesting efficiency through temperature, molecular orientation and interlayer separation in TMD/organic heterostructures.

Schottky junction photodiode based on graphene—organic semiconductor heterostructure

The isolation of graphene on an insulating substrate has provided new opportunities for the fabrication of electronic devices with radically new geometries and structures. The use of single-layer graphene as an electrode has enabled the development of novel electronic device architectures that exploit the unique atomically thin structure of the material, which also includes a low density of states at its charge neutrality point. In this work, we present the first example of a vertical Schottky junction photodiode based on the graphene—organic semiconductor–metal heterostructure. The n-type N,N′-dioctyl-3,4,9,10-perylenedicarboximide (PTCDI-C8) organic semiconductor was thermally deposited onto chemical vapor deposition (CVD)-grown single-layer graphene. The tunable Schottky injection barrier permitted tuning of the diode rectification ratio by more than two orders of magnitude upon application of gate biases, which increased the photocurrent but suppressed the dark current of the photodiodes. Tuning of the photovoltaic properties of the devices was also confirmed, indicating that the device architecture based on the work function tunability of graphene could provide a versatile strategy for enhancing the performance of organic photodiodes.

A feasible heterostructure of P(VDF-TrFE)/semiconductor for a stable multi-state memory

Abstract Ferroelectric random-access memory is widely concerned because of its nearly infinite writing cycles and fast reading and writing ability. Since ferroelectric memory is not as dense as dynamic random-access memory and static random-access memory, which cannot store so much data in the same space, it is difficult to replace these technologies in practical applications. One possible solution to this dilemma is to increase the storage capacity per memory cell. This work uses a feasible capacitor structure of P(VDF-TrFE)/organic semiconductor heterostructure to improve the storage capacity. Both ferroelectric layer and semiconductor layer are prepared using a simple spin coating method. Due to the intervention of semiconductor, three polarization states are demonstrated owing to the splitting of a displacement current peak, where the semiconductor-dielectric transformation of the semiconductor layer plays an important role. The measurement of electrical properties shows that the ferroelectric thin film about this structure with three polarization states can be used to represent the storage 0, 1, 2, and the polarization of P1, P2, P3 are 0, 3.4 and 9.2 μC cm−2, respectively. According to the fitting results, the data retention capacity of this structure is excellent, that the residual polarizations of P1, P2 and P3 are 0, 3.2 and 9.2 μC cm−2 over 3 months, respectively.

A block copolymer of crosslinkable polythiophene and removable poly(ethylene oxide) for preparing heterostructures of organic semiconductors

Block copolymer films composed of polythiophene with cinnamate groups and poly(ethylene oxide) were prepared as template networks of donor/acceptor heterostructures.

Long-Range Embedding of Molecular Ions and Excitations in a Polarizable Molecular Environment.

We present a method for evaluating electrostatic and polarization energies of a localized charge, charge transfer state, or exciton embedded in a neutral molecular environment. The approach extends the Ewald summation technique to polarization effects, rigorously accounts for the long-range nature of the charge-quadrupole interactions, and addresses aperiodic embedding of the charged molecular cluster and its polarization cloud in a periodic environment. We illustrate the method by evaluating the density of states and ionization energies in thin films and heterostructures of organic semiconductors. By accounting for long-range mesoscale fields, we obtain the ionization energies in both crystalline and mesoscopically amorphous systems with high accuracy.

Fabrication of ultra-fine nanostructures using edge transfer printing

The exploration of new methods and techniques for application in diverse fields, such as photonics, microfluidics, biotechnology and flexible electronics is of increasing scientific and technical interest for multiple uses over distance of 10-100 nm. This article discusses edge transfer printing--a series of unconventional methods derived from soft lithography for nanofabrication. It possesses the advantages of easy fabrication, low-cost and great serviceability. In this paper, we show how to produce exposed edges and use various materials for edge transfer printing, while nanoskiving, nanotransfer edge printing and tunable cracking for nanogaps are introduced. Besides this, different functional materials, such as metals, inorganic semiconductors and polymers, as well as localised heating and charge patterning, are described here as unconventional "inks" for printing. Edge transfer printing, which can effectively produce sub-100 nm scale ultra-fine structures, has broad applications, including metallic nanowires as nanoelectrodes, semiconductor nanowires for chemical sensors, heterostructures of organic semiconductors, plasmonic devices and so forth.

Use of Thin Sectioning (Nanoskiving) to Fabricate Nanostructures for Electronic and Optical Applications

This Review discusses nanoskiving--a simple and inexpensive method of nanofabrication, which minimizes requirements for access to cleanrooms and associated facilities, and which makes it possible to fabricate nanostructures from materials, and of geometries, to which more familiar methods of nanofabrication are not applicable. Nanoskiving requires three steps: 1) deposition of a metallic, semiconducting, ceramic, or polymeric thin film onto an epoxy substrate; 2) embedding this film in epoxy, to form an epoxy block, with the film as an inclusion; and 3) sectioning the epoxy block into slabs with an ultramicrotome. These slabs, which can be 30 nm-10 μm thick, contain nanostructures whose lateral dimensions are equal to the thicknesses of the embedded thin films. Electronic applications of structures produced by this method include nanoelectrodes for electrochemistry, chemoresistive nanowires, and heterostructures of organic semiconductors. Optical applications include surface plasmon resonators, plasmonic waveguides, and frequency-selective surfaces.

Organic‐organic heteroepitaxy: facts, concepts and perspectives

AbstractOrganic‐organic heteroepitaxy can represent the winning technique for growing crystalline and oriented heterostructures of organic semiconductors. However, a sound physical interpretation of mechanisms that control epitaxy is still missing for these low symmetry molecular systems, generally not obeying the usual lattice matching rules for inorganic systems. We discuss here a couple of paradigmatic examples of organic‐organic heteroepitaxy suggesting a possible physical rationale for the formation of the heterostructure interfaces as it arises from experimental characterization and computer modeling with atom‐atom potential simulations. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Light-emitting organic field-effect transistor using an organic heterostructure within the transistor channel

The authors have realized a light-emitting organic field-effect transistor. Excitons are generated at the interface between a n-type and a p-type organic semiconductor heterostructure inside the transistor channel. The dimensions and the position of the p-n heterostructure are defined by photolithography. The p-n heterostructure is at a distance of several microns from the metal electrodes. Therefore, the exciton and photon quenching in this device is reduced. Numerical simulations fit well with the experimental data and show that the light-emitting zone can move within the transistor channel.

Raman Monitoring of Organic Semiconductor Heterostructure Formation

Raman Monitoring of Organic Semiconductor Heterostructure Formation

Raman Monitoring of Organic Semiconductor Heterostructure Formation

Raman Monitoring of Organic Semiconductor Heterostructure Formation