Looking for a research student - Photoluminescence-based characterisation methods for perovskite solar cells

Looking for a research student - PhD at the University of New South Wales, Sydney, Australia

Topic: Photoluminescence-based characterisation methods for perovskite solar cells

Contact: Dr Ziv Hameiri (ziv.hameiri@unsw.edu.au).

Of interest
Scholarships at UNSW
Graduate Research at UNSW


PhD at the University of New South Wales, Sydney, Australia

The School of Photovoltaic and Renewable Energy Engineering (SPREE) is one of the nine schools within the Faculty of EngiPhD at the University of New South Wales, Sydney, Australia

The School of Photovoltaic and Renewable Energy Engineering (SPREE) is one of the nine schools within the Faculty of Engineering at University of New South Wales (UNSW), Sydney, Australia. SPREE grew out of the Australian Research Council Photovoltaics Centre of Excellence in response to the growing industry of renewable energy. The school is widely considered as the best in the world. Building on its world-leading research, the school attracts leading international researchers in the area of photovoltaic.

Our academic staff has been consistently ranked amongst the leaders worldwide in the photovoltaic field through international peer review. Our team has held the world record for silicon solar cell efficiencies for over twenty years and has been responsible for developing the most successfully commercialised new photovoltaic technology internationally throughout the same period. The solar cell technology that predicted to dominate the market in the next decade (the ‘PERC’) was invented and developed in our school.

We are looking for an excellent student for a novel project involving new solar cell technology and advanced inspection tools (details below). The PhD project will be done in our state-of-the-art laboratories, using our advance fabrication and characterisation facilities.

Suitable students will be awarded with a full scholarship for 3.5 years (PhD duration in Australia is 3-3.5 years). The scholarship fully covers the university fees and provides additional allowance to cover living costs:

Tuition fees: $45,000 per year

Living allowance: ~$27,000 per year

Conference allowance: $3,000 per conference (to support attending a scientific international conferences; at least two conferences during the PhD).

Requirements:

Undergraduate Degree: Bachelor degree in a scientific or engineering discipline specialising in chemistry, material, physics, electrical and electronic, or mechatronic with a graduation GPA above 8 out of 10, or equivalent.

Master Degree: Graduation from a Master by research program, focusing on perovskite, organic or dyes solar cells. At least one international journal publication in a relevant research area is required.

Supervision will be done by Dr Ziv Hameiri and Dr Xiaojing (Jeana) Hao.

For more details please contact Dr Ziv Hameiri (ziv.hameiri@unsw.edu.au).

Photoluminescence-based characterisation methods for perovskite solar cells

In the past few years a new class of solar cell based on mixed organic-inorganic hybrid perovskite has stunned the photovoltaic community. Although the first efficiency of solid-state perovskite of 9.7% was reported only in 2012, rapid progress by several research groups has improved this efficiency to an independently confirmed one above 20% earlier this year. Within a couple of years perovskite solar cells achieved similar efficiency to those of much more mature thin-film solar cell technologies (such as CdTe and CIGS), which took up to ten times as long to reach similar efficiencies. Development of various fabrication methods and several device structures suggest that this efficiency is still far from its limit.

Despite the astonishing performance improvement in such a short time, perovskite-based solar cells suffer from some major problems. One key challenge for this technology is the stability of the devices; they tend to undergo degradation (sometimes within only a few hours), especially upon exposure to moisture. Another challenge associated with perovskite-based solar cells, which is common to all thin film solar cell approaches, is the cell uniformity. The latter determines the ability to scale-up the impressive efficiencies achieved on small devices to larger areas. To date, perovskite solar cells have been fabricated mostly on relatively small substrates (5–30 mm2). However, commercial applications require a much larger substrate area (in the order of 156 mm × 156 mm). This scaling-up requires the ability to monitor the uniformity of the fabrication process. Lateral process variations can be expected particularly for solution spreading techniques that are often implemented in the fabrication of perovskite solar cells.

The rapid progress in the fabrication technology of perovskite solar cells has not been accompanied by the development of dedicated characterisation methods. The uniqueness of perovskite-based solar cells and the strong need for dedicated characterisation methods is obvious when considering the challenges researchers face to perform a simple current–voltage measurement for this type of device. Surprisingly, it was found that the current often depends on the bias voltage applied to the cell before the measurement is taken.

Note that the world record for silicon solar cell efficiency that had been held by UNSW over the last few decades was strongly supported by the availability of state-of-the-art characterisation tools and the resulting ability to analyse loss mechanisms. In order to further improve the efficiencies of perovskite-based solar cell, innovative analysis methods need to be developed.

Aims:

The aim of this project is to develop luminescence-based imaging methods to characterise spatially resolved recombination and degradation mechanisms within perovskite-based solar cells.

Photoluminescence (PL) – the emission of light from a material after the absorption of photons – has been proven to be a very powerful monitoring tool for silicon-based solar cells. PL imaging is a measurement approach that was developed at UNSW and is commonly used for silicon wafers and silicon solar cells. Since the first proof of concept studies in the characterisation labs in SPREE, this technology has seen rapid adoption worldwide by researchers and companies and is now one of the most widely used techniques. For silicon devices, PL imaging is frequently used to monitor essential electrical parameters such as minority carrier lifetime, implied open circuit voltage, diode saturation currents, series resistance, shunt resistance, and pseudo fill factor. The contactless nature of the measurement and the fact it can be performed even on non-completed devices makes it an ideal tool to investigate various limiting processes within silicon wafers and silicon solar cells. UNSW has an internationally leading position in the growth of PL as an effective characterisation tool for silicon photovoltaic. This project will benefit from the large knowledge and experiences in SPREE on various PL technologies to develop groundbreaking PL imaging methods for perovskite solar cells.

The main project aims are to:

• Develop physical models that correlate emitted PL signal to electrical properties of the solar cells, such as implied open-circuit voltage and diode saturation current.

• Develop methods to extract essential solar cells parameters, such as series resistance and pseudo fill factor, from PL images.

• Investigate recombination mechanisms within perovskite solar cell using PL and identifying the main loss mechanisms that limit efficiency.

• Investigate the degradation processes associated with perovskite solar cell.

• Investigate the uniformity of various processing methods and assessing the losses associated with the non-uniformity.

 

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