PhD thesis - 'Electronic Processes at the Interface of Organic Semiconductors'

TL;DR

This thesis investigates the optical and photovoltaic properties of organic heterostructures, optimizing their preparation for use in efficient organic solar cells and photoconverters by analyzing morphology, surface, and electrical properties.

Contribution

It introduces optimized fabrication conditions for organic heterostructures with enhanced solar energy absorption and charge separation capabilities, applying models from inorganic semiconductors.

Findings

Optimal conditions for film preparation identified.

Heterostructures absorb most solar radiation in visible and near infrared.

Models from inorganic semiconductors successfully describe organic heterostructures.

Abstract

The thesis focuses on study of optical and photovoltaic properties of iso-type and aniso-type heterostructures based on photosensitive layers of organic semiconductors. The primary attention has been paid on determination of optimal conditions for preparation of organic thin-film structures of methyl substituted perylene pigment, hexathiopentacene and SnCl2 phthalocyanine. These structures are perspective for fabrication of photosensitive heterostructures and can be used for development of effective photoconverters of solar energy. The influence of annealing and substrate temperature during thermal deposition of the films on morphology and surface structure, optical and photovoltaic properties of thin films of methyl substituted perylene pigment, hexathiopentacene and SnCl2 phthalocyanine was studied. The surface and bulk parameters of considered films were determined from the results obtained here. The photovoltaic and optical properties of organic iso-type and aniso-type heterostructures prepared on the substrates with different temperatures were studied. The obtained data for heterostructures were analyzed using Anderson model and Van Opdorp model, respectively. This analysis showed that organic aniso-type heterostructures based on methyl substituted perylene pigment and iso-type heterostructures based on pentacene can be described by the models proposed and developed for inorganic semiconductor heterojunctions. The optimal conditions were determined for preparation of organic photosensitive heterostructures, which absorb most part of solar radiation in visible and near infrared range, as well as effectively generate and separate charge carriers on the interface of heterojunction. The aniso-type and iso-type heterostructures prepared under optimal conditions are perspective elements for development of organic photoconverters, including organic solar cells.