WIN Research Celebration

Greetings

Lisa Pokrajac, WIN Assistant Director, Research Programs, WIN

Greetings

Charmaine Dean, Vice President Research & International, UWaterloo

Welcoming remarks and introduction of WIN Rising Star recipients

Sushanta Mitra, Executive Director, WIN

Keynote lecture by WIN Rising Star Recipient Robert Hoye, Professor at London Imperial College

'Defect Tolerant Semiconductors for Clean Energy Harvesting – Nanomanufacturing and Emerging Materials'

Photovoltaics produce clean electricity from sunlight and are one of the critical renewable technologies for achieving net-zero emissions targets and fulfilling UN Sustainable Development Goals on affordable and clean energy. Although silicon has become the most widely used photovoltaic material, its efficiency has approached its fundamental limit. Furthermore, many of the new consumers of energy will be small autonomous devices part of the Internet of Things ecosystem. Although solar cells are regarded as an ideal way to power these devices, silicon does not have the optimum band gap for indoor light harvesting. The past decade has witnessed the emergence of a new class of lead-halide perovskites, which have rapidly increased in efficiency in photovoltaic devices. A critical enabling factor is the tolerance of the halide perovskites to defects, enabling long charge carrier lifetimes to be achieved despite high densities of defects when the materials are manufactured at low-temperature using simple solution-based methods. These halide perovskites have wider band gaps than silicon and can be combined together with silicon devices in tandem photovoltaics that could exceed the efficiency limits of single-junction silicon solar cells. However, the toxicity of the water-soluble lead component of halide perovskites is a potential barrier to large-scale adoption.

The first part of this talk examines scalable nanomanufacturing methods for perovskite-silicon tandem devices. Specifically, atmospheric pressure chemical vapor deposition (AP-CVD) is put forward as an alternative to solution processing, thermal evaporation and atomic layer deposition for growing the thin (~10 nm) inorganic buffer layer. This is critical for protecting the lead-halide perovskite absorber and organic charge transport layers from mechanical damage when the transparent top electrode is deposited by sputtering. We show that AP-CVD grows pinhole-free n-type and p-type oxides within minutes without vacuum. But the soft deposition results in negligible damage to the perovskite, and the highly dense oxide layers reduce leakage current, leading to improved efficiency [1,2].

The second part of this talk examines bismuth-based semiconductors as a non-toxic and air-stable alternative to lead-halide perovskites. We demonstrate through computations and experiment that bismuth oxyiodide (BiOI) replicates the defect tolerance of the lead-halide perovskites [3,4]. BiOI has a band gap of 1.9 eV, which is suitable for top-cells in tandems with silicon, and we achieve devices with up to 80% external quantum efficiency at 450 nm wavelength [3]. Moreover, the band gap of BiOI is ideal for indoor light harvesting, and we show that the BiOI solar cells are already comparable to hydrogenated amorphous silicon (the industry standard) under indoor lighting. We discuss the current limiting factors for BiOI solar cells and how efficiencies could be improved in the future, as well as the potential of the broader perovskite-inspired materials family for indoor light harvesting.  

11:00AM-11:45AM

Keynote lecture by WIN Rising Star Recipient Drew Higgins, Professor at McMaster University

'Electrocatalyst development for electrochemical CO₂ conversion into fuels and chemicals and future research needs for this technology'

For electrochemical energy conversion and storage technologies to become viable component of future sustainable energy infrastructures, the development of catalysts that are active, selective, stable and inexpensive is required. The first portion of this talk will focus on catalysts for electrochemical reduction of CO₂ to produce industrially relevant fuels and chemicals. While these products are generally fossil fuel derived, electrochemical CO₂ reduction (CO₂R) provides opportunity to use renewable energy (i.e., wind, solar, hydro) as the energy input to achieve a carbon-neutral artificial photosynthesis process. This talk will introduce the concept and fundamentals underlying electrochemical CO₂ reduction. The talk will then highlight recent work on the development of nanostructured carbon catalysts containing atomically dispersed nickel-nitrogen-carbon (Ni-N-C) active sites for the conversion to CO₂ into carbon monoxide, including their synthesis, characterization, and activity/selectivity evaluation. A discussion of the remaining challenges facing electrochemical CO₂R technology development will then be provided.

11:45AM-11:55AM

Recognition of WIN Research Leader with their awards

Sushanta Mitra, Executive Director, WIN

Recognition of 2020 WIN Nanofellowship recipients 

Sushanta Mitra, Executive Director, WIN