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Xiamen-Cardiff Seminar

Colloidal Quantum Dots: 0D Materials for Next-Generation Photovoltaics

Speaker: Bo Hou (Cardiff University)
Date: Friday 22 October 2021
Time: 9:30
Venue: Zoom

Colloidal metal chalcogenide quantum dots (QDs), as a typical 0D material, have excellent quantum efficiency in light-matter interactions and good device stability. Although QDs have been brought to the forefront as viable building blocks in bottom-up assembling semiconductor devices, the development of QD solar cells (QDSCs) is still confronting considerable challenges comparing to other QD technologies due to their low performance under natural sunlight [1-5]. This talk is about our recent works and the prospect of addressing this long-standing challenge. We conducted preliminary research on the feasibility of using QDSC under abnormal photon irritation such as indoor and concentration PV (CPV) applications. We found that bandgap photon energy irradiation of QD solids can generate high densities of excitons via multi-photon absorption (MPA) and multiple exciton generation (MEG). Furthermore, these excitons are not limited to diffuse by Auger recombination up to 1.5*1019 cm-3 densities irradiance. Based on these findings, we demonstrated a 19.5% (2000 lux indoor light) and an 11.6% efficiency (1.5 Suns) QDSCs could be facilely realized from an ordinary QDSCs (9.55% under 1 Sun). To further illustrate the MPA's potential in QDSCs, a 21.29% efficiency polymer lens CPVs (4.08 Suns) and viable sensor networks powered by indoor QDSCs matrix have been demonstrated.6 We believe these initial works could provide some suggestions on the development of next-generation Photovoltaics: such as using the potential of the quantized density-of-state from 0D materials [1,2].

1. Colloidal Quantum Dots: The Artificial Building Blocks for New-Generation Photo-Electronics and Photochemistry, Isr. J. Chem. 2019, 59, 637.
2. Indoor photovoltaics, The Next Big Trend in solution-processed solar cells, InfoMat. 2021, 3, 445-459.
3. Highly Monodispersed PbS Quantum Dots for Outstanding Cascaded-Junction Solar Cells, ACS Energy Lett. 2016, 1, 4, 834–839.
4. Chemically encoded self-organized quantum chain supracrystals with exceptional charge and ion transport properties, Nano Energy 2019, 62, 764-771.
5. Colloidal quantum dot hybrids: an emerging class of materials for ambient lighting, J. Mater. Chem. C, 2020, 8, 10676-10695.
6. Multiphoton Absorption Stimulated Metal Chalcogenide Quantum Dot Solar Cells under Ambient and Concentrated Irradiance, Adv. Funct. Mater. 2020, 30, 2004563.

Short bio: Dr Bo Hou is a University Lecturer (tenured assistant professor) at the School of Physics and Astronomy, Cardiff University. He received his PhD degree from the University of Bristol (2010–2014) and worked as a postdoctoral researcher at the University of Oxford (2014–2018, Wolfson College) and a Senior Research Fellow in the Department of Engineering at the University of Cambridge (2018-2020, St Edmund's College). He is an international expert (>90 publications, h-index=24) in solution-processed quantum materials for PV and smart lighting and beyond. He made several ground-breaking demonstrations in technologies based on solution-processed compound semiconductor quantum dots (QDs), including the 1st demonstration of high-performance indoor QDPV, cascaded-junction excitonic QDPV with efficiency above 15% and novel QD superstructures for emerging optoelectronic, display and ambient lighting applications. He is the PI and recipient of several awards and grants, including EPSRC, Royal Society of Chemistry, etc.