Elucidating understanding and realising device improvements in halide perovskite tandem cells through construction of a high-throughput characterisati

Perovskite solar cells (PSCs) have rapidly become the most promising emerging photovoltaic technology. Less than a decade since their inception, PSCs have already achieved power conversion efficiencies comparable to silicon solar cells, the current market leader. This rapid development can be explained by the excellent optoelectronic properties of lead halide perovskites, such as high absorption coefficients and long carrier diffusion lengths, facile synthesis routes yielding high quality material and the possibility to tune material properties, such as the bandgap, by compositional engineering. Bandgap tuning makes it possible to make a perovskite tandem solar cell, where two sub-cells with a different bandgap perovskite are stacked on top of each other, allowing more efficient harvesting of the solar spectrum.
Single junction PSCs have been studied using a wide range of techniques and device physics are increasingly well understood. This is much less the case for tandem devices, in part because research interest is only building now, but mainly because of the increased complexity of these device systems. The number of layers and interfaces is more than doubled, making design and understanding of photonic in-coupling and electronic charge collection a technical challenge, but one of paramount importance. In addition, processes in one of the sub-cells often cannot be studied fully independently from the other sub-cell.
As fabrication and measurements are very time consuming, typically a minimal amount of samples is studied. This has led to contradictory and poorly reproducible reports in literature. In this project we aim to develop new high-throughput electronic and optical characterisation methods and use these to further our understanding of the energetic and photonic properties of tandem PSCs.
Objectives
Objective 1: Design and build a high-throughput setup to study optoelectronic processes at individual interfaces in tandem devices under operation.
Objective 2: Measure fundamental electrical properties of tandem PSCs using the custom-built setup and study how these properties evolve under operating conditions (bias and illumination).
Objective 3: Simulating device behaviour including photonic structures to maximise light absorption and device performance.

The impact of the CDT in Connected Electronic and Photonic Systems is expected to be wide ranging and include both scientific research and industry outcomes. In terms of academia, it is envisaged that there will be a growing range of research activity in this converged field in coming years, and so the research students should not only have opportunities to continue their work as research fellows, but also to increasingly find posts as academics and indeed in policy advice and consulting.

The main area of impact, however, is expected to be industrial manufacturing and service industries. Relevant industries will include those involved in all areas of Information and Communication Technologies (ICT), together with printing, consumer electronics, construction, infrastructure, defence, energy, engineering, security, medicine and indeed systems companies providing information systems, for example for the financial, retail and medical sectors. Such industries will be at the heart of the digital economy, energy, healthcare, security and manufacturing fields. These industries have huge markets, for example the global consumer electronics market is expected to reach $2.97 trillion in 2020. The photonics sector itself represents a huge enterprise. The global photonics market was $510B in 2013 and is expected to grow to $766 billion in 2020. The UK has the fifth largest manufacturing base in electronics in the world, with annual turnover of £78 billion and employing 800,000 people (TechUK 2016). The UK photonics industry is also world leading with annual turnover of over £10.5 billion, employing 70,000 people and showing sustained growth of 6% to 8% per year over the last three decades (Hansard, 25 January 2017 Col. 122WH). As well as involving large companies, such as Airbus, Leonardo and ARM, there are over 10,000 UK SMEs in the electronics and photonics manufacturing sector, according to Innovate UK. Evidence of the entrepreneurial culture that exists and the potential for benefit to the UK economy from establishing the CDT includes the founding of companies such as Smart Holograms, PervasID, Light Blue Optics, Zinwave, Eight19 and Photon Design by staff and our former PhD students. Indeed, over 20 companies have been spun out in the last 10 years from the groups proposing this CDT.

The success of these industries has depended upon the availability of highly skilled researchers to drive innovation and competitive edge. 70% of survey respondents in the Hennik Annual Manufacturing Report 2017 reported difficulty in recruiting suitably skilled workers. Contributing to meeting this acute need will be the primary impact of the CEPS CDT.

Centre research activities will contribute very strongly to research impact in the ICT area (Internet of Things (IoT), data centre interconnects, next generation access technologies, 5G+ network backhaul, converged photonic/electronic integration, quantum information processing etc), underpinning the Information and Communications Technologies (ICT) and Digital Economy themes and contributing strongly to the themes of Energy (low energy lighting, low energy large area photonic/electronics for e-posters and window shading, photovoltaics, energy efficient displays), Manufacturing the Future (integrated photonic and electronic circuits, smart materials processing with photonics, embedded intelligence and interconnects for Industry 4.0), Quantum Technologies (device and systems integration for quantum communications and information processing) Healthcare Technologies (optical coherence tomography, discrete and real time biosensing, personalised healthcare), Global Uncertainties and Living with Environmental Change (resilient converged communications, advanced sensing systems incorporating electronics with photonics).