We are building the ultimate light-harvesting system by efficient conversion and transport of excitons.
This involves spectral and spatial manipulation of the solar spectrum, with downshifting and upconversion to compress broadband sunlight into a narrow band for efficient harvesting by next-generation, solution-processed excitonic solar cells. This theme delivers new, light-harvesting concepts and novel, full-spectrum materials for next-generation, low-cost, high-efficiency excitonic light-harvesting devices.
Theme 1 comprises two research platforms; Excitonic Light Management (Platform 1.1) and Solution-Processed Next Generation Photovoltaics (Platform 1.2). Currently the fundamental maximum theoretical efficiency for conversion of light into current for a single solar cell, called the Shockley-Queisser (SQ) limit, is approximately 30% for Si based technology. Combined, these Theme 1 Platforms seek to design hybrid solar cell systems which can surpass the SQ limit.
Exciton Science members at Monash University study a prototype photovoltaic cell
The goal of this platform is to tame the solar spectrum, by controlling the energy and spatial dimension of light. By doing this we aim to exceed the 34% Shockley-Queisser efficiency limit for light-to-electricity energy conversion.
Photochemical upconversion is the process of converting two low-energy photons into one of higher energy. Designing materials which can exploit this process would allow us to utilise energy from the infrared part of the sun’s spectrum and transform it into higher energy so it can be converted into electric current.
Luminescent solar concentration is a process whereby the energy density of light hitting a surface can be increased by concentrating the light absorbed over a large area into a much smaller area via waveguiding. A Luminescent Solar Concentrator (LSC) can improve the efficiency of upconversion and also allow solar energy collection to be integrated into building architecture.
The Wong Group at University of Melbourne completed the characterisation of fluorescent polymer nanoparticles for LSCs and a manuscript has been submitted.
Progress has has been made in the optimisation of violanthrone derivatives which are promising emitters for upconversion systems below the silicon band gap. A manuscript in preparation for submission in early 2024. Contribution were made by Dr Anjay Manian (RMIT) on theoretical calculations on new violanthrones.
The magnetic field effect on upconverted emission from diphenylanthracene trimers was measured by Dr Philip Feng (UNSW) with unusual behaviour observed. We are awaiting theoretical modelling to help exlpain the results.
Efforts have been made to determine the reason for the difficulty in obtaining high-performing LSC and upconversion devices.
We have gained better understanding of:
In collaboration with our industry partner, ClearVue Technologies Limited (ASX:CPV) (www.clearvuepv.com), we conducted optical measurements on a range of PVB laminates, as requested by the Lawrence Berkeley National Laboratory (LBNL) in California. This project is aimed at providing a detailed characterization of ClearVue's laminates, ensuring their inclusion in the International Glazing Database (IGDB) and enhancing future versions of the WINDOW 7.8 software. This enhancement improved the software's capability to evaluate the thermal and optical properties of glazing materials.
The outcome was mentioned in the publication: www.sustainable-buildings-journal.org/articles/sbuild/full_html/2023/01/sbuild20230003/sbuild20230003.html
QD–dye systems are promising models for artificial photosynthesis and down-converter systems for LEDs and displays. To better understand the factors controlling energy transfer from the QDs to the dyes, we fabricated a series of CdxZn1–xS/ZnS quantum dot (QD)-perylene diimide (PDI) composite nanocrystals.
(Wu et al.)
Naphthalene diimides (NDIs) are a common class of chromophores used in photon harvesting applications due to their functional malleability through substitution of the NDI core. However, some derivatives with substitution at the imide position of the NDI core only become emissive in electron-rich aromatic solvents. This study examines this phenomenon from both an experimental and theoretical perspective, in order to understand how NDIs interact with each other and the surrounding medium upon photoexcitation.
(Pervin et al.)
Industry: The Mulvaney and Ghiggino groups are still working with ClearVue PV on solar windows. A postdoc with industry experience, Qingrui Kong, was hired in 2023 to work on quantum dot-polymer integration in films in close collaboration with ClearVue PV. A connection has been established with Melbourne Safety Glass to investigate local manufacturing options for solar windows..
Our priority is to achieve efficient solid-state upconversion devices and to achieve a dye/quantum dot-based LSC with performance exceeding published benchmarks.
Beyond this, we aim to design guidelines and develop understanding of the physical chemical aspects of upconversion systems to allow the development of efficient solid-state upconversion devices and to demonstrate an improved LSC dye/nanocrystal formulation that offers commercial potential.
Platform 1.2 aims to investigate emerging materials within solar cell architectures that can go beyond traditional silicon in efficiency or utility.
This is being achieved by developing new materials and device architectures through advanced theoretical and synthetic combinatorial screening approaches, advanced device simulation and characterisation methods.
We are developing microstructurally controlled solar cell absorbers on graphene electrodes and microstructurally controlled, lead-free and NIR thin films.
We are attempting to quantitatively describe the operation of a solar cell based on a new material or optoelectronic phenomenon and are seeking to experimentally validate the predictions of a simulated solar cell device based on simulated material properties.
We are continuing to advance perovskite materials and their solar cells and develop lead-free solar cell materials. We are working on semi-flexible silicon solar cells for use in alternative photovoltaic applications.
The Melbourne Centre of Nanofabrication commissioned a unique combinatorial sputtering system with in-situ characterization to accelerate materials development, alongside tools to assess solar cell performance under UV and thermal cycling. Their high-throughput energy materials discovery platform completed factory acceptance testing in November 2023 and was shipped to Australia in December 2023.
In 2022, Exciton Science supported the commercialization of a new conductive coating technology, leading to further funding in 2023 from the Office of National Intelligence and Australia’s Economic Accelerator, and the spin-out of Green Shield Solutions.
A theoretical framework was developed for identifying promising photovoltaic absorber materials, focusing on perovskite-like materials, and identifying six candidates from over 129,000 for further exploration and optimization via in-silico simulations.
Two force fields for simulating perovskite formation, including direct nucleation from solution and two-step processing, have been developed to understand the effects of processing conditions and additives on perovskite formation.
Simulations were used to understand the thermodynamic forces affecting metal halide perovskite formation and stability, including the roles of light and heat in mixed-halide perovskites and the effectiveness of MACl in wide bandgap perovskite solar cells.
Functionalized, imidazolium-based phosphonic acids were developed for interfacial passivation in perovskite solar cells, showing modest work-function shifts but no major efficiency improvements when used as SnO2 electron transport replacements.
Research on novel hole transport layers led to the development of strontium-modified NiO nanoparticles, creating a hierarchical hole-transporting layer for perovskite solar cells, improving efficiency to over 20% and stability to over 95% after 1000 hours.
Lead acetate was identified as a promising precursor for methylammonium lead halide perovskite solar cells, offering more efficient and stable cells than the lead iodide route, with a novel synthesis route developed for formamidinium caesium lead halide perovskites.
Collaboration with Prof. Henry Snaith’s group at Oxford University led to the discovery that adding dimethylammonium salts to perovskite precursor-solution forms intermediate phases, improving film orientation, performance, and stability through subsequent thermal annealing.
Research on CZTS as an alternative solar cell material to silicon continued, with a focus on its cost-effectiveness and abundance, achieving an 11.1% efficiency milestone in collaboration with a solar cell project.
Research on perovskite solar cells for X-ray detection demonstrated their high efficiency in detecting both soft and hard X-rays, leading to the development of fully flexible and scalable all-printed devices.
Flexible silicon solar cell modules, developed in partnership with Woodside Energy, focused on module design optimization and environment testing, leading to a provisional patent submission for the work.
Metal halide perovskite based tandem solar cells are promising to achieve power conversion efficiency beyond the theoretical limit of their single-junction counterparts. Here, a holistic approach to overcoming challenges in 1.8 eV perovskite solar cells is reported by engineering the perovskite crystallization pathway by means of chloride additives.
(Shen et al.)
The reversal of halide ions is studied under various conditions. However, the underlying mechanism of heat-induced reversal remains unclear. This work finds that dynamic disorder-induced localization of self-trapped polarons and thermal disorder-induced strain (TDIS) can be co-acting drivers of reverse segregation.
(Mussakhanuly et al.)
CuSCN Modified Back Contacts for High Performance CZTSSe Solar Cells
(Ji et al.)
Photovoltaic thin film solar cells based on kesterite Cu2ZnSn(S, Se)4 (CZTSSe) have reached 13.8% sunlight-to-electricity conversion efficiency. To tackle this issue, a new window structure ZnO/AgNW/ZnO/AgNW (ZAZA) comprising layers of ZnO and silver nanowires (AgNWs) is proposed.
(Ji et al.)
Major staff changes following COVID-19 have induced reshaping of key research groups aligned to this platform. As such, progress has slowed as recovery of group cohorts is initiated.
Industry - Dr Noel Duffy (CSIRO), Mitsuru Imaiizumi (JAXA), Chris Ryan (CSIRO), Jitendra Joshi (Woodside Energy, Boon Siaw (Woodside Energy)
International - Obadiah Reid (NREL), Federico Pulvirenti, Stephen Barlow, Seth R. Marder (Georgia Institute of Technology & University of Colorado Boulder, USA), Jian Wang, Yangwei Shi, David Ginger (University of Washington, USA), Sandheep Ravishankar (Forschungszentrum Jülich), Takeshi Ohshima (QST), Dr Ben Diroll (Argonne National Lab), Laura Herz and Henry Snaith (Oxford).
In 2024, we will complete several perovskite formation studies, focusing on two-step formation, precursor thermodynamics, and crystal growth mechanisms. Research on chiral perovskites and nanocrystals has begun.
We're also exploring non-lead solar cell materials, particularly complex metal oxides and binary metal antimonides, using various deposition methods.
Our solar windows project will advance semi-opaque perovskite solar cells. These devices, already showing promising colour-neutrality and performance, will be developed using solution processing and molecular imprinting to achieve over 30% transparency and over 15% efficiency.
For the CZTS Work Package, we aim to scale up the optimal solar cell design and discuss commercialization with partners like Wuhan Institute of Technology and Prof Yibing Cheng. Chang-Qi Ma from Suzhou, a key partner, is interested in prototype development at their Suzhou printing centre.
Finally, our semi-flexible silicon project will progress with tailored architectures for module development, focusing on scalability, electrical, mechanical, and environmental stability, aiming for a spin-out in Q2 2024.
News - Step change in upconversion the key to clean water, green energy & futuristic medicine
Theme 2: Control of Excitons