Organic-inorganic Heterostructures Research Articles

Growth and physical properties of molecular organic thin films

Highly-oriented polycrystalline thin films of molecular organic materials consisting of small molecules can be easily obtained by physical and chemical vapour deposition methods. The crystallographic phase, orientation and morphology of the films critically depend on the interface and on the kinetics of growth and can be controlled, to a certain extent, by a judicious selection of the substrates and of the growth parameters. This article shortly explores the formation of organic-inorganic heterostructures as a function of coverage: from the most fundamental case, a single molecule on a surface, to thick films (thickness 1 μm). The case of high-quality thick TTF-TCNQ films exemplifies the fact that the derived physical properties are essentially identical to those obtained from single crystals.

Ultraviolet light selective photodiode based on an organic–inorganic heterostructure

We show a perfect ultraviolet (UV) light selective and sensitive photovoltaic cell easily fabricated. The device consists of a water-soluble p-type semiconducting polymer PEDOT-PSS: poly(3,4-ethylenedioxythiophene) doped by poly(4-styrenesulfonate) film deposited on a Nb-doped titanium oxide (SrTiO3:Nb) substrate. For the PEDOT-PSS/SrTiO3:Nb heterostructure, the photosensitivity at zero bias for the UV light with L=1 mW/cm2 is estimated to be 0.05 A/W, corresponding to a quantum yield of 16% electron/photon. This device is only activated in the UV region (λ<390 nm), and then, it exhibits a large response to the UV–B light (290–320 nm).

Preparation of Organic-Inorganic Hybridized Materials using Photopolymerization

Organic-inorganic semiconductor heterostructures have been successfully fabricated by incorporating a polydiacetylene backbone into layered perovskite compounds by photopolymerization. The n -ray irradiation caused polymerization of aminodiacetylene cations, RNH 3 + , where R=CH 3 (CH 2 ) 13 C L C-C L CCH 2 , in the solid salts of (RNH 3 ) 2 PbBr 4 . Layered Perovskite Photopolymerization Quantum-well

Electronic Bandstructure and Transport Properties of Self-Organised Organic-Inorganic Heterostructures

We have calculated the hybrid bandstructure formed by the self-organisation of discotic (disk-like) liquid crystal molecules on an ultra-thin Au film. The discotic molecules stack into columns which exhibit one-dimensional transport. When deposited on an inorganic surface, the columns self-organise into a long-range ordered 2-dimensional hexagonal array. The interaction at the surface perturbs the metallic bandstructure, and the regular, periodic nature of the organic overlayer results in the formation of new, hybrid bands. The adsorption and the quantum mechanical coupling between the metallic states and the localised molecular orbitals are modelled by the Newns-Anderson Hamiltonian. The conductivity changes of the film are computed using the Kubo-Greenwood formula.

Organic-inorganic heterojunction electroluminescent device fabricated by conjugated polymer and zinc oxide

In this study an organic-inorganic heterostructure device was fabricated. This hybird device consisted of two layers, one of which was a conjugated polymer layer and the other an inorganic material layer. Compared with a single conjugated polymer layer device of the same thickness, the emission intensity increases about 5-8 times. The inorganic layer plays the role of the electron-transport layer similar to its organic heterojunction counterpart.

Optical Stark effect of hybrid excitons in organic-inorganic heterostructures

In two-dimensional heterostructures made of semiconductor and organic layers in which the respective Wannier and Frenkel excitons are in resonance, the lowest electronic excitations are of a hybrid nature. The results of a microscopic model calculation of the optical Stark effect in such hybrid excitons are presented and discussed. Significant quantitative and qualitative differences are found with respect to the well-known case of semiconductor quantum wells. In particular, depending upon the specific choice of polarization, a novel, dramatically non-monotonic dependence on detuning is predicted.

Hybrid excitons in organic-inorganic semiconducting quantum dots

We investigate the nonlinear optical susceptibility and the radiative decay rate of a new excitonic state in organic-inorganic heterostructures. These hybrid excitons could appear due to resonant mixing of Wannier-Mott and Frenkel excitons. The aim of our investigation is to examine the nonlinear optical properties of this new hybrid state for the quantum dot geometry. We will show that the new hybrid state has an enhanced optical nonlinearity as compared to the basic states and, at the same time, a large oscillator strength.

Organic-inorganic heterostructure electroluminescent device using a layered perovskite semiconductor (C6H5C2H4NH3)2PbI4

Using the combination of a layered perovskite compound (C6H5C2H4NH3)2PbI4 (PAPI), which forms a stable exciton with a large binding energy owing to its low-dimensional semiconductor nature and exhibits sharp and strong photoluminescence from the exciton band, and an electron-transporting oxadiazole derivative, we fabricated an organic–inorganic heterostructure electroluminescent (EL) device. The EL spectrum of the device corresponded well to the photoluminescence spectrum of the PAPI film; the emission was peaking at 520 nm and half-width of the emission was about 10 nm at liquid-nitrogen temperature. Further, highly intense EL of more than 10 000 cd m−2 was performed at 2 A cm−2 at liquid-nitrogen temperature in the device.