Two-for-one photon conversion in synthetic proteins for energy harvesting
Lead Research Organisation:
University of Sheffield
Department Name: Physics and Astronomy
Abstract
Project Description:
Singlet fission is a process whereby one photon creates two excited states. This two-for-one mechanism could dramatically increase solar cell efficiency (from 33% to >40%). Recently, there has been much academic and industrial interest in developing new singlet fission sensitizers, but to-date no material has proved ideal [1].
Carotenoids are the most widespread of the natural pigments, important for photosynthesis, vision, human health and industry (market value $1.2bn). Surprisingly, carotenoids are also excellent candidates for singlet fission sensitizers, demonstrating strong absorption and fast (<100fs) singlet fission [2]. However, problems remain: the mechanism of singlet fission and how to control it is not yet understood in carotenoids, and - crucially - it is not yet clear how to transfer the pairs of excited states into a photovoltaic for solar energy harvesting.
This PhD project tackles these problems using our brand-new synthetic carotenoid-bound-proteins, which demonstrate singlet fission, smooth film formation and increased pigment stability. The student will explore the possibility of using the unique properties of our proteins to facilitate radiative transfer from the carotenoids to the solar cell, creating films that convert single high energy photons into pairs of low-energy photons.
[1] Nature Reviews 2017, 2, 17063. [2] JACS, 2015, 137, 5130.
Aims, Objectives & Methodology:
We have recently created a new range of synthetic 'maquette' proteins that bind carotenoids in a specific dimer configuration, demonstrate rapid (<100fs) singlet fission, improved pigment stability and form smooth films. The main aim of this project is to exploit the protein scaffold and induce light emission from the singlet-fission generated excited-states: creating thin films that convert one high energy photon into two low-energy photons. To this end, the student will explore two methods:
(1) soaking the protein in heavy elements [1]. The close proximity of the carotenoid pi-conjugated backbone to the heavy elements in the protein core will encourage phosphorescence through external spin-orbit coupling, similar to that recently demonstrated in organic light emitting diodes [2]. It is expected that the confining nature of the protein core (which can be constrained or loosened by changing the protein design) will reduce non-radiative decay (similar to 'aggregation-induced emission' [3]), resulting in efficient phosphorescence;
(2) tethering the proteins to emissive PbSe nanoparticles [4]. An alternative method is that of transferring the triplet states to emissive nanoparticles with the correct energetics. The simple design motif of the proteins will allow the student to tether the proteins directly on to the nanoparticles [5], placing the carotenoids at the ideal location for efficient carotenoid-to-nanoparticle transfer.
By the end of the project, we hope the student will be able to create protein-based thin film coatings for high efficiency (eg. silicon) solar cells.
References:
1] Pike Acta Crystal. D Struct. Biol., 2016, 72, 303. [2] Bolton Nat. Chem., 2011, 3, 207. [3] Yuning Hong 2016 Methods Appl. Fluoresc. 4 022003 [4] Tabachnyk Nat. Mater., 2014, 13, 1033. [5] Boles Nat. Mater., 2016, 15, 141.
Alignment to EPSRC's portfolio:
This is a fundamental and very interdisciplinary project. It therefore falls across many growth areas of EPSRC's portfolio: all the way from 'materials for energy applications' through 'chemical biology' to 'biophysics and soft matter'. It even touches on the grand challenges: 'nanoscale design of functional materials' and 'understanding the physics of life'. In addition, training the future scientists across multiple disciplines, as in this project, is an important component of the government's Industrial Strategy.
This is a collaborative project between physics and biology. No companies are involved at present.
Singlet fission is a process whereby one photon creates two excited states. This two-for-one mechanism could dramatically increase solar cell efficiency (from 33% to >40%). Recently, there has been much academic and industrial interest in developing new singlet fission sensitizers, but to-date no material has proved ideal [1].
Carotenoids are the most widespread of the natural pigments, important for photosynthesis, vision, human health and industry (market value $1.2bn). Surprisingly, carotenoids are also excellent candidates for singlet fission sensitizers, demonstrating strong absorption and fast (<100fs) singlet fission [2]. However, problems remain: the mechanism of singlet fission and how to control it is not yet understood in carotenoids, and - crucially - it is not yet clear how to transfer the pairs of excited states into a photovoltaic for solar energy harvesting.
This PhD project tackles these problems using our brand-new synthetic carotenoid-bound-proteins, which demonstrate singlet fission, smooth film formation and increased pigment stability. The student will explore the possibility of using the unique properties of our proteins to facilitate radiative transfer from the carotenoids to the solar cell, creating films that convert single high energy photons into pairs of low-energy photons.
[1] Nature Reviews 2017, 2, 17063. [2] JACS, 2015, 137, 5130.
Aims, Objectives & Methodology:
We have recently created a new range of synthetic 'maquette' proteins that bind carotenoids in a specific dimer configuration, demonstrate rapid (<100fs) singlet fission, improved pigment stability and form smooth films. The main aim of this project is to exploit the protein scaffold and induce light emission from the singlet-fission generated excited-states: creating thin films that convert one high energy photon into two low-energy photons. To this end, the student will explore two methods:
(1) soaking the protein in heavy elements [1]. The close proximity of the carotenoid pi-conjugated backbone to the heavy elements in the protein core will encourage phosphorescence through external spin-orbit coupling, similar to that recently demonstrated in organic light emitting diodes [2]. It is expected that the confining nature of the protein core (which can be constrained or loosened by changing the protein design) will reduce non-radiative decay (similar to 'aggregation-induced emission' [3]), resulting in efficient phosphorescence;
(2) tethering the proteins to emissive PbSe nanoparticles [4]. An alternative method is that of transferring the triplet states to emissive nanoparticles with the correct energetics. The simple design motif of the proteins will allow the student to tether the proteins directly on to the nanoparticles [5], placing the carotenoids at the ideal location for efficient carotenoid-to-nanoparticle transfer.
By the end of the project, we hope the student will be able to create protein-based thin film coatings for high efficiency (eg. silicon) solar cells.
References:
1] Pike Acta Crystal. D Struct. Biol., 2016, 72, 303. [2] Bolton Nat. Chem., 2011, 3, 207. [3] Yuning Hong 2016 Methods Appl. Fluoresc. 4 022003 [4] Tabachnyk Nat. Mater., 2014, 13, 1033. [5] Boles Nat. Mater., 2016, 15, 141.
Alignment to EPSRC's portfolio:
This is a fundamental and very interdisciplinary project. It therefore falls across many growth areas of EPSRC's portfolio: all the way from 'materials for energy applications' through 'chemical biology' to 'biophysics and soft matter'. It even touches on the grand challenges: 'nanoscale design of functional materials' and 'understanding the physics of life'. In addition, training the future scientists across multiple disciplines, as in this project, is an important component of the government's Industrial Strategy.
This is a collaborative project between physics and biology. No companies are involved at present.