Australian Centre for Advanced Photovoltaics Australia-US Institute for Advanced Photovoltaics Annual Report 2014 Never Stand Still Engineering Photovoltaic and Renewable Energy Engineering Stanford University Table of Contents 1. Director’s Report 2 2. Highlights 4 40% Sunlight to Electricity Conversion 4 First 20% Efficient Cells Using Low-Cost Solar-Grade Silicon 4 Stuart Wenham receives Harvey Research Prize 5 Student Awards 2014 5 High Impact Papers 5 High Performance Organic Photovoltaics Using Nematic Liquid Crystals 6 Compact CH3NH3PbI3 for High Efficiency Perovskite Cells 6 High Efficiency Perovskite Solar Cell 7 3D Printing of Perovskite Solar Cells 7 3. Organisational Structure and Research Overview 8 4. Affiliated Staff and Students 10 University of New South Wales 10 Australian National University 11 CSIRO (Materials Science and Engineering, Melbourne) 12 University of Melbourne 12 Monash University 12 University of Queensland 13 Arizona State University (QESST 13 National Renewable Energy Laboratory 13 Sandia National Laboratories 13 Molecular Foundry 13 Stanford University 13 Georgia Technology Institute 13 University of California, Santa Barbara 13 Wuxi Suntech Power Co. Ltd. 13 BT Imaging 13 Changzhou Trina Solar Energy Co. Ltd. 13 Australian Centre for Advanced Photovoltaics - Annual Report 2014 BlueScope Steel 13 5. Research Reports 14 Program Package 1 Silicon Cells 14 PP1.1 Solar Silicon 15 PP1.2 Rear Contact Silicon Cells 17 PP1.3 Silicon Tandem Cells 21 Program Package 2 Thin-Film, Third Generation and Hybrid Devices 32 PP2.1 Organic Photovoltaic Devices 33 PP2.2 Thin film Inorganic (CZTS) 53 PP2.3 Superstrate Liquid-Phase Crystallised Silicon on Glass Cells 56 PP2.4 Third Generation Approaches 58 Program Package 3 Optics/Characterisation 69 PP3.1 Methods to characterize the optical and electrical properties of organic and other thin film earth abundant solar cell 70 PP3.2 Light Trapping 71 Program Package 4 Manufacturing Issues 77 PP4 Cost Evaluations 77 Program Package 5 Education, Training and Outreach 79 PP5.1 ACAP Wide Activities 79 PP5.2 UNSW Led Activities 82 PP5.3 ANU Led Activities 90 PP5.4 UQ led activities 90 PP5.5 UoM led activities 91 PP5.6 Monash led activities 91 PP5.7 CSIRO led activities 92 6. AUSIAPV International Activities 94 6.1 40% efficient ‘Power Cube’ power tower receiver 95 6.2 Metal Complexes as Solid-state Hole Conducting Materials 97 6.3 Carrier selective contacts for boosting Si solar cell efficiency 98 6.4 Solar Cell Performance Documentation 100 6.5 PV Factory 100 7. Financial Summary 102 8. Publications 103 8.1 Books 103 8.2 Book Chapters 103 8.3 Patent Applications 104 8.4 Papers in Refereed Scientific and Technical Journals 104 8.5 Conference Papers and Presentations 109 8.6 Theses 116 8.7 Report 116 8.8 Research Training Tool 116 Table of ContentsTable 1 1. Director’s Report Photovoltaics involves the direct AUSIAPV/ACAP came into being on 1 February 2013 after the signing of a Head Agreement production of electricity from between University of New South Wales (UNSW) light, especially sunlight, when it and ARENA. Subsequently, collaborations were established between UNSW and the other ACAP falls upon devices known as solar nodes, Australian National University (ANU), cells. Silicon is the most common University of Melbourne (UoM), Monash University, University of Queensland (UQ) and CSIRO material used to make these (Materials Science and Engineering, Melbourne) photovoltaic cells, similar to its key and additionally with the ACAP industrial partners, role in microelectronics, although Suntech Research and Development, Australia (SRDA) (now Wuxi Suntech Power Co. Ltd.), a range of other photovoltaic Changzhou Trina Solar Energy Co. Ltd., Bluescope materials is being actively Steel and BT Imaging. Further, partnerships were established with the major international investigated. participants, the NSF-DOE Engineering Research Center for Quantum Energy and Sustainable This is the second annual report of the Solar Technologies (QESST) and the US National Australia-US Institute for Advanced Renewable Energy Laboratory (NREL), as well as Photovoltaics(AUSIAPV), supported by the from additional key US partners, Sandia National Australian Government through the Australian Laboratories, The Molecular Foundry, Berkeley, Stanford University, Georgia Institute of Technology Renewable Energy Agency (ARENA) for an initial and the University of California, Santa Barbara. eight-year period. The Institute encompasses the activities of the locally based Australian This report covers the period from 1 January to 31 Centre for Advanced Photovoltaics (ACAP) December 2014. As well as setting up the broad as well as synergistic international activities framework for collaboration on an international with US-based partner organisations. scale, both AUSIAPV and ACAP have moved very quickly to establish a high profile within the AUSIAPV aims to significantly accelerate international research community. Following on photovoltaic development beyond that achievable from the world-record 24.4% energy conversion by Australia or the US individually. This goal is to be efficiency cell developed at ANU during 2013 and reached by leveraging the development of “over the confirmed early in 2014, a second world record horizon” photovoltaic technology, thereby providing was demonstrated later in 2014. A system based a pipeline of improved technology for increased on splitting focused sunlight into four different performance and reduced cost. A second aim is colour bands, designed and fabricated at UNSW to provide high-quality training opportunities for then tested at US partner NREL, became the first the next generation of photovoltaic researchers, to convert sunlight to electricity with over 40% particularly through enhanced collaborations energy conversion efficiency. These and several of between Australian and US researchers, with the other highlights over the year are summarised Australian Centre for Advanced Photovoltaics – Annual Report 2014 one goal being to consolidate Australia’s position in the pages immediately following my report. as the photovoltaic research and educational 2 hub of the Asia-Pacific manufacturing region. This report covers the period from 1 January to 31 December 2014. As well as setting up the broad framework for collaboration on an international scale, both AUSIAPV and ACAP have moved very quickly to establish a high profile within the international research community. Other achievements outlined in the body of this 2014 Annual Report contributed to making 2014 an extremely successful year for the Institute. The photovoltaic industry fared better than most other industries through the recent global financial crisis and is now growing vigorously as costs continue to go down, driven by the ongoing uptake of improved technology that ACAP is uniquely positioned to supply. As an indicator of the growing appreciation of the large role photovoltaics will play in future energy supply, Bloomberg New Energy Finance brought forward to 2016 the company’s forecast date for when photovoltaics would surpass coal generators worldwide as the largest source of new electricity generation capacity. I would like to thank ARENA for ongoing financial support and also for the very effective involvement of ARENA personnel in supporting the AUSIAPV/ACAP program, both informally and via the ACAP National Steering Committee and the AUSIAPV International Advisory Committee. I would additionally like to thank, in particular, all researchers affiliated with the Institute for their contributions to the broad range of progress reported in the following pages. Martin Green Director Finally, I am pleased to be able to report that AUSIAPV/ACAP has taken its second major step towards attaining its significant long-term objectives by achieving all second year milestones, on time and within budget. We look forward to a similar result in 2015 and in subsequent years. 1. Director’s Report 3 2. Highlights 40% Sunlight to First 20% Efficient Cells Electricity Conversion Using Low-Cost Solar- The program attained a landmark result internationally in 2014 with the first demonstration Grade Silicon of sunlight conversion to electricity with efficiency Researchers at the Australian National University above 40%. In an AUSIAPV project supported by ACAP node have demonstrated the world’s first ARENA, UNSW, NREL and commercial partners, silicon solar cell with greater than 20% efficiency, RayGen Resources Pty Ltd and Spectrolab using silicon wafers made with 100% ‘solar-grade’ Inc., a 287 cm2 aperture area prototype was silicon feedstock (see Section PP1.1). The n-type constructed by combining a commercial triple- silicon wafers were supplied by industry partner junction III-V concentration solar cell with a Apollon Solar, and were grown using Upgraded commercial silicon cell in a 4-junction system. Metallurgical-Grade silicon material (UMG Si), a low- Innovative bandpass filtering was used to achieve cost and low-energy refining process that promises the required partitioning of the solar spectrum to reduce both the cost and energy-intensity of so that currents in the III-V cell were balanced. silicon solar cells. Using a cell fabrication process that has been modified to maintain high electronic The 40% landmark efficiency was first measured quality in the UMG wafers, a peak efficiency of in outdoor testing in Sydney in October 2014, 20.1% was achieved, as measured at ANU, almost after which the system was shipped