Final Report Summary - HYBRIDS (Hybrid Semiconductors: Design Principles and Material Applications)
The field of hybrid organic-inorganic semiconductors has rapidly over the past 5 years. This project was well placed to inform and direct these developments using a set of predictive materials modeling tools based on computational chemistry.
Throughout the project we have published 50 research papers, presented invited and keynote lectures, and built a set of bespoke simulation tools. We constructed a set of design principles for describing the properties of hybrid solids, which can be classified into four areas:
1. Optical Engineering of Metal-Organic Frameworks
We have identified a number of approaches for controlling the optical absorption onset of hybrid frameworks, through modification of the metal and organic components. We can selectivity control the absolute energies of the valence band (ionization potential) and conduction band (electron affinity). One approach – amination of organic ligands – has been used to make better visible light photocatalysts through valence band modification.
2. Electronic Engineering of Metal-Organic Frameworks
The effective transport of electron and hole charge carriers in hybrid materials is a challenge, which we have addressed by considering the orbital overlap between the two primary components in hybrid frameworks. This has allowed us to identify the optimal metal and ligand combinations for electrical conductivity and magnetism, e.g. effective magnetic superexchange can be achieved when Mn is combined with a twisted acetylene dicarboxylate.
3. Hybrid Materials for Photovoltaic Applications
Hybrid organic-inorganic perovskites are arguably the most exciting development in solar energy research since the success of Si devices in the 1950s. The materials can be solution processed at low temperatures and still result in high light-to-electricity conversion efficiencies. We have used electronic structure theory to explain: (i) why these materials work so well, which includes strong relativistic renormalization of the band structure and collective motions of the dipolar molecular components; (ii) how we can go beyond the current lead-containing materials.
4. Disorder in hybrid materials
Hybrid materials can contain static and dynamic disorder, both of which can have implications for their practical application. Static disorder can be present in the form of defects while dynamic disorder arises from thermally activated switching between energetically similar configurations. Through our studies of defects and thermal disorder we have established important links between microscopic structural features and macroscopic properties, e.g. the hydrogen bonding in hybrid perovskites and the measurable ferroelectricity arising from ordering of the cations.
Together these four streams represent a significant step towards a roadmap for producing novel functional materials combining organic and inorganic building blocks.
Throughout the project we have published 50 research papers, presented invited and keynote lectures, and built a set of bespoke simulation tools. We constructed a set of design principles for describing the properties of hybrid solids, which can be classified into four areas:
1. Optical Engineering of Metal-Organic Frameworks
We have identified a number of approaches for controlling the optical absorption onset of hybrid frameworks, through modification of the metal and organic components. We can selectivity control the absolute energies of the valence band (ionization potential) and conduction band (electron affinity). One approach – amination of organic ligands – has been used to make better visible light photocatalysts through valence band modification.
2. Electronic Engineering of Metal-Organic Frameworks
The effective transport of electron and hole charge carriers in hybrid materials is a challenge, which we have addressed by considering the orbital overlap between the two primary components in hybrid frameworks. This has allowed us to identify the optimal metal and ligand combinations for electrical conductivity and magnetism, e.g. effective magnetic superexchange can be achieved when Mn is combined with a twisted acetylene dicarboxylate.
3. Hybrid Materials for Photovoltaic Applications
Hybrid organic-inorganic perovskites are arguably the most exciting development in solar energy research since the success of Si devices in the 1950s. The materials can be solution processed at low temperatures and still result in high light-to-electricity conversion efficiencies. We have used electronic structure theory to explain: (i) why these materials work so well, which includes strong relativistic renormalization of the band structure and collective motions of the dipolar molecular components; (ii) how we can go beyond the current lead-containing materials.
4. Disorder in hybrid materials
Hybrid materials can contain static and dynamic disorder, both of which can have implications for their practical application. Static disorder can be present in the form of defects while dynamic disorder arises from thermally activated switching between energetically similar configurations. Through our studies of defects and thermal disorder we have established important links between microscopic structural features and macroscopic properties, e.g. the hydrogen bonding in hybrid perovskites and the measurable ferroelectricity arising from ordering of the cations.
Together these four streams represent a significant step towards a roadmap for producing novel functional materials combining organic and inorganic building blocks.