Research
Theme 1
Excitonic Systems for Solar Energy Conversion
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.
Excitonic Light Management (Platform 1.1)
What’s this platform about?
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.
Progress in 2022
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:
- the effects of excimer formation in upconversion;
- alignment effect in nanorods;
- the dynamics in a LSC at high concentrations;
- singlet fission;
- and oxygen effect on upconversion.
Research Highlights
CIs Wallace Wong and Tim Schmidt collaborated with AI Angèle Reinders on the paper ‘Simulations of Luminescent Solar Concentrator Bifacial Photovoltaic Mosaic Devices Containing Four Different Organic Luminophores’, published in IEEE.
This international collaboration focused on simulating different architectures and composition of LSC devices via Monte Carlo Simulation. Our colleagues then progressed to experimentally constructing these devices and determining their performance.
Risk/issue mitigation
We are concerned about losing key skills and capabilities upon the conclusion of some students PhDs, including Roslyn Forecast and Michael Rinaudo, who has developed the Centre’s capability to do optical modelling of nanorods in LSCs.
We have been seeking new students to pass this knowledge to, but there continues to be a shortage of PhD applicants as a consequence of the COVID-19 pandemic.
Collaborations
Industry: ClearVue is an informal commercial partner on aspects of Mulvaney and Ghiggino’s research, investigating the use of quantum dots into window laminates, which could potentially be extended to upconversion. Kirkwood and Mulvaney have also initiated discussions with BlueDot Photonics on thin films perovskites upconverting layers.
Outlook for next year
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.
Solution-Processed Next Generation Photovoltaics (Platform 1.2)
What’s this platform about?
Platform 1.2 aims to investigate emerging materials within solution-processed solar cell architectures that can go beyond 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 novel charge transport layers and interfacial modifications to support higher efficiency and stability solution-processed perovskite solar cells.
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 have attempted to demonstrate fully optimized perovskite solar cells and a lead-free solar cell with a record efficiency. Understanding continues to be sought regarding the origins of instability of perovskite solar cells.
Progress in 2022
Major infrastructure developments are underway, including a robotic materials platform, combinatorial sputtering system, and a time-correlated single-photon counting (TCSPC) confocal Raman microscope.
We are developing advanced photovoltaic simulation capability that can harness machine learning and AI to provide greater insights into real devices with thin film and back-contact geometries.
Progress is being made in force field development to support nucleation of perovskites and two-step processing.
We are simulating perovskite solar cells under different device architectures and predicting the device performance for identified visible and NIR solar cell materials mined from existing databases.
Work on advanced charge transport layers has demonstrated low-temperature processed SnO2 nanoparticles can serve as electron selective charge transport layers for high-efficiency printed perovskites.
Work on solar windows has focused on advanced compositional engineering applied to perovskites which has resulted in semi-transparent perovskite solar cells being developed with record efficiencies across most average visible transmittance values below 40% and with stability factors exceeding 1000 hours of operational lifetime.
Work is continuing on back-contact perovskite solar cells, employing compositional and interfacial engineering methods to reduce the hysteresis and improve the stabilised efficiency up to 10.9%.
We are also seeking to demonstrate a semi-opaque perovskite solar cell with a 10% efficiency at a 10% average visible light transmittance, and a photovoltaic device harnessing a novel NIR material predicted from big data machine learning filtering tools.
Research Highlights
Phase-Control of Single-Crystalline Inorganic Halide Perovskites via Molecules Coordination Engineering, Advanced Functional Materials 32 (16), 2109442.
Stable Aqueous SnO2 Nanoparticle Dispersion for Roll-to-Roll Fabrication of Flexible Perovskite Solar Cells. Coatings 12(12): 1948.
High‐Performance and Stable Semi‐Transparent Perovskite Solar Cells through Composition Engineering. Advanced Science 9(22): 2201487.
Efficient and stable formamidinium-caesium perovskite solar cells and modules from lead acetate-based precursor. Energy & Environmental Science 2023(16):138-147
Back-contact perovskite solar cell fabrication via microsphere lithography. Nano Energy 102 (2022):107695
A Stable Aqueous SnO2 Nanoparticle Dispersion for Roll-to-Roll Fabrication of Flexible Perovskite Solar Cells. Coatings 12(12):1948
Risk/mitigation
Dr Tian Zhang finished his role as lab manager at Monash. This has left a major capability gap around training, maintenance and operationalisation within the renewable lab.
A lot of senior expertise has been lost during and post COVID in solar cells across the Monash node. This has made capability continuity very challenging, and is resulting in productivity challenges for the platform.
Outlook for next year
Materials for solar cells
A site acceptance test is planned for the high-throughput materials discovery platform in 2023.
We intend to extend the method to identify materials suitable for various other photovoltaic functions as part of the ab-initio Novel Photovoltaic Material Discovery (Machine Learning) package of work.
We intend to use techniques in perovskite crystal growth from solution simulation to characterise the precursor dynamics, interfacial structure, mechanism of growth, and thermodynamic barriers for a range of conditions.
For inorganic perovskite CsPbIBr2 crystallization and microstructures, we aim to understand solid phase crystallization dynamics and focus on performance optimisation of Cs-based all-inorganic perovskite solar cells with influences from twin domains.
Device Fabrication and Characterisation
Work will continue on integration of printable perovskite diodes with external readout electronics to perform real time imaging of target objects for dual X-ray energy detection.
Development continues in advanced optical-electrical imaging techniques for perovskite solar materials, with devices from various nodes and external collaborators now under examination.
We aim to perform a full irradiation series on space-grade perovskite solar cells developed in Sydney.
Novel Photovoltaic Concepts
Patterned perovskites will be a key focus to achieve high-efficiency semi-opaque solar cell architectures.
Module development on glass and plastic substrates continues for semi-transparent perovskite solar cells.
Module development for light-weight silicon solar cells will continue through advanced lamination and coating approaches.