arXiv subjects

Dionysios Papadatos

Publications and source records attributed to Dionysios Papadatos.

3 recordsLinked to original sources

arXiv2016

Yellow Light Energy Transfer Emitting Diodes Based on mixed Quasi-2D Perovskites

The new class of hybrid organic-inorganic semiconductor (HOIS) materials, based on halide perovskites, is constantly being pursued for applications such as Light Emitting Diodes (LEDs) and solar cells, due to their momentous optoelectronic properties. In this work, we present a single layer LED that operates due to energy transfer effects as well as a simple, instant and low cost method for its fabrication. A LED device based on a mixture of zero dimensional (OD) (CH 3 NH 3 ) 4 PbI 6, two dimensional (2D) (F- C 6 H 4 CH 2 CH 2 NH 2 ) 2 PbI 4 and three dimensional (3D) (CH 3 NH 3 )PbI 3 HOIS, is presented for the first time. The final composite material manifests simple, yet unique energy transfer optical effects, while its electroluminescence exhibits excitonic recombination bright yellow light, peaked at 592 nm. LED device fabricated under ambient air, readily functions at room temperature and low voltages. As for the active layer, it exhibited substantial film continuity in any form of deposition. Finally, with appropriate mixtures, it is possible to create films containing phase changes that exhibit dual color emission, here presented as yellow-green.

physics.optics↗

arXiv2016

Mixtures of quasi-two and three dimensional hybrid organic-inorganic semiconducting perovskites for single layer LED

New blends of simply synthesized quasi two-dimensional (quasi-2D) hydrophobic perovskite semiconductors, employed in high performance light emitting diodes (LEDs) which function due to excitonic energy transfer effects, are reported. These materials are self-assembled blends of 2D, quasi-2D and three-dimensional (3D) hybrid organic-inorganic semiconductors (HOIS). Moreover, shown for the first time, crude mixing of 3D perovskite and unprotonated amines provides similar semiconductors. HOIS reported here are based on the organic cations CH3NH3+, CH3(CH2)7CH=CH(CH2)8NH3+ or C6H5CH2CH2NH3+ and inorganic networks formed out of PbX42- anions (X=I, Br, Cl). HOIS exhibit strong bound excitonic states with increased oscillator strength at room temperature, tunable via simple halide substitution. HOIS blends manifest energy transfer effects, where adjacent nanoparticles of different band gap energies (Eg) transfer optical energy to those with the lowest Eg; the suggested light emission mechanism here. LED fabrication is attained via a single deposition of the hydrophobic mixture, reducing device complexity, cost and degradability. LED's diodic behavior is observed even under light albeit its photovoltaic and photoconductive quasi-2D and 3D components. LED devices exposed for over than four months under adverse laboratory conditions, showed stable light emission. Further research on this class of quasi-2D/3D HOIS mixtures is expected to lead to novel quantum electronic devices.

cond-mat.mtrl-sci↗

arXiv2016

Unique Room Temperature Light Emitting Diode Based on 2D Hybrid Organic-Inorganic Low Dimensional Perovskite Semiconductor

A Light Emitting Diode (LED) based on a two dimensional (2D) Hybrid Organic-Inorganic Semiconductor (HOIS) functioning at room temperature is demonstrated. LED is fabricated by depositing a layer of (4-fluorophenethylamine-H)2PbI4 on an ITO substrate. It is the first time that such a room temperature excitonic LED based on 2D lead iodide perovskite is presented, as well as for its simplicity, low cost, ambient conditions fabrication and functioning at 5-10V. The newly introduced class of 3D HOIS perovskite LEDs, is now broadened with the implementation of the 2D HOIS. Novel functionalities can be realized since it is now possible to access the hybrid's 2D semiconductor advantageous properties, such as increased excitonic binding energy, oscillator strength and peak wavelength tunability.

physics.chem-ph↗