Photoluminescence and electroluminescence imaging of perovskite solar cells

Fast camera‐based luminescence‐imaging measurements on perovskite solar cells are presented. The fundamental correlation between the luminescence intensity and the open circuit voltage predicted by the generalised Planck law is confirmed, enabling various quantitative methods for the detection of efficiency‐limiting defects to be applied to this new cell structure. Interstinegly, it is found that this fundamental correlation is valid only for light‐soaked devices. Copyright © 2015 John Wiley & Sons, Ltd.     

Photovoltaics literature survey (No. 115)

In order to help keep readers up‐to‐date in the field, each issue of Progress in Photovoltaics will contain a list of recently published journal articles that most relevant to its aims and scope. This list is drawn from an extremely wide range of journals, including IEEE Journal of Photovoltaics, Solar Energy Materials and Solar Cells, Renewable Energy, Renewable and Sustainable Energy Reviews, Journal of Applied Physics, and Applied Physics Letters. To assist the reader, the list is separated into broad categories, but please note that these classifications are by no means strict. Also note that inclusion in the list is not an endorsement of a paper's quality. If you have any suggestions please email Ziv Hameiri at ziv.hameiri@unsw.edu.au     

Photovoltaics literature survey (No. 128)

In order to help readers stay up‐to‐date in the field, each issue of Progress in Photovoltaics will contain a list of recently published journal articles that are most relevant to its aims and scope. This list is drawn from an extremely wide range of journals, including IEEE Journal of Photovoltaics, Solar Energy Materials and Solar Cells, Renewable Energy, Renewable and Sustainable Energy Reviews, Journal of Applied Physics and Applied Physics Letters. To assist readers, the list is separated into broad categories, but please note that these classifications are by no means strict. Also note that inclusion in the list is not an endorsement of a paper's quality. If you have any suggestions please email Ziv Hameiri at ziv.hameiri@unsw.edu.au . Copyright © 2016 John Wiley & Sons, Ltd.     

Laser induced defects in laser doped solar cells

Laser doping offers a promising method to define selective emitters for solar cells. Its main advantage is the localised nature of the laser beam, which allows melting of the surface area without heating the bulk. The ability to perform this process over a dielectric film offers further benefits, such as the possibility of creating self‐aligned metallisation patterns simultaneously with the selective emitter formation. However, laser induced defects, contaminations and discontinuities in the selective emitter can reduce solar cell performance. In this work the influence of different dielectric films on defect formation is investigated. It was found that a thin oxide beneath the SiN_x improves the implied open circuit voltage of the solar cells for a wide range of laser output powers. Fewer defects were observed when using this SiO₂/SiN_x stack compared to the standard single SiN_x anti‐reflection coating layer. It was also found that the recrystallised silicon layer grows epitaxially according the substrate orientation. No dislocation or stacking faults were observed in deeper areas using transmission electron microscopy, although some defects were observed near the surface. Electron beam induced current images revealed discontinuities in junctions formed with high laser powers. We conclude that micro‐cracks create these discontinuities, which can potentially induce shunts. Finally, laser doped solar cells with a standard SiN_x and with a double SiO₂/SiN_x stack layer as anti‐reflection coating were compared. An efficiency of 18.4% on a large area commercial grade p‐type CZ substrate was achieved. Copyright © 2010 John Wiley & Sons, Ltd.     

Advantages of photoplating for laser doped solar cells

The use of laser doping in solar cell fabrication has received increased attention in recent years, especially due to its ability to form a selective emitter without subjecting the wafer to prolonged high temperature processes and likely corresponding degradation. At the University of New South Wales, a novel laser doping method was developed that combines the formation of the selective emitter with a self‐aligned metallisation pattern. This paper investigates the influence of different plating methods on shunt and enhanced recombination regions. It was found that the pseudo fill factors of solar cells plated using photoplating are higher compared to those plated with the electroless method, indicating reduced shunting and/or junction recombination. The superiority of the photoplating method is even more pronounced at high laser powers. According to our knowledge this is the first time photoplating and electroless plating techniques have been compared for laser‐doped solar cells. Copyright © 2011 John Wiley & Sons, Ltd.     

Estimating the principal curvatures and the Darboux frame from real 3-D range data

Principal curvatures and the local Darboux frame are natural tools to be used during processes which involve extraction of geometric properties from three-dimensional (3-D) range data. As second-order features their estimations are highly sensitive to noise and therefore, until recent years, it was almost impractical to extract reliable results from real 3-D data. Since the use of more accurate 3-D range imaging equipment has become more popular, as well as the use of polyhedral meshes to approximate surfaces, evaluation of existing algorithms for curvature estimation is again relevant. The work presented here, makes some subtle but very important modifications to two such algorithms, originally suggested by Taubin (1995) and Chen and Schmitt (1992). The algorithms have been adjusted to deal with real discrete noisy range data, given as a cloud of sampled points, lying on surfaces of free-form objects. The results of this linear time (and space) complexity implementation were evaluated in a series of tests on synthetic and real input. We also present one of many possible uses for these extracted features in an efficient and robust application for the recovery of 3-D geometric primitives from range data of complex scenes. The application combines the segmentation, classification and fitting processes in a single process which advances monotonously through the recovery procedure. It is also very robust and does not use any least-squares fittings. The conclusion of this study is that with current scanning technology and the algorithms presented here, reliable estimates of the principal curvatures and Darboux frame can be extracted from real data and used in a large variety of tasks.     

Photovoltaics literature survey (No. 117)

In order to help keep readers up‐to‐date in the field, each issue of Progress in Photovoltaics will contain a list of recently published journal articles that are most relevant to its aims and scope. This list is drawn from an extremely wide range of journals, including IEEE Journal of Photovoltaics, Solar Energy Materials and Solar Cells, Renewable Energy, Renewable and Sustainable Energy Reviews, Journal of Applied Physics, and Applied Physics Letters. To assist the reader, the list is separated into broad categories, but please note that these classifications are by no means strict. Also note that inclusion in the list is not an endorsement of a paper's quality. If you have any suggestions please email Ziv Hameiri at ziv.hameiri@unsw.edu.au .