Use this URL to cite or link to this record in EThOS:
Title: PEDOT:PSS-based hybrid materials for optoelectronics applications
Author: Occhi, Luca
ISNI:       0000 0004 7427 7221
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 2017
Availability of Full Text:
Access from EThOS:
Access from Institution:
Organic electronics is a research area that, in recent year, has received increasing attention both from academia and industry. Performance of organic optoelectronic devices, such as organic light-emitting diodes (OLEDs) and organic photovoltaic devices (OPVs), relies on the electrical and optical characteristics of each component. However, the performance are frequently limited by the distribution of the internal electromagnetic field: an effective light management, involving either the incoupling of incident radiation (in case of photovoltaic cells and photo-detectors), or the outcoupling of emitted light (for light-emitting diodes), is crucial. The electric field distribution may be optimised by adjusting the device geometry or, alternatively, by modifying the optical properties (i.e. refractive index and absorption coefficient) of each component. Developing a material with tunable optical properties, whilst maintaining acceptable electrical characteristics, would offer a significant alternative in high-performance devices. Among the different compounds used in organic devices, the charge injection/extraction materials play a key role: the ubiquitous poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) is an example of an organic compound often limited (in thickness) by the optical losses. In this work we introduce an innovative, solution-processable, inorganic/organic hybrid material based on PEDOT:PSS, which could be used as an efficient hole-transport layer, or as an electrode, in OLEDs and OPVs. The hybrid system exhibits high optical quality, a dramatic increase of refractive index (up to +12-13%), and a decrease in work function, whilst maintaining good electrical conductivity. We prove the effectiveness of our approach both by modeling the distribution of normalised modulus squared of the optical electric field in light-emitting structures. Furthermore, we fabricate and characterise optoelectronic devices (OLEDs and OPVs) with PEDOT:PSS hybrid hole-transport layers, demonstrating an increase of efficiency in the organic light-emitting diodes. Finally, we investigate the thermoelectric properties of hybrid material, thus opening interesting new applications for our hybrid compound.
Supervisor: Bradley, Donal D. C. ; Stavrinou, Paul N. ; Stingelin, Natalie Sponsor: Engineering and Physical Sciences Research Council
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral