ORCID Profile
0000-0002-3860-5633
Current Organisations
University of New South Wales
,
UNSW Sydney
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Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/D0TA04863A
Abstract: Three kesterite thin-film solar cells, Cu 2 ZnSnSe 4 (CZTSe), Cu 2 ZnSn(S,Se) 4 (CZTSSe), and Cu 2 ZnSnS 4 (CZTS), and based on low light intensity measurements, examined the possibility of using kesterite devices for indoor applications.
Publisher: Elsevier BV
Date: 04-2020
Publisher: IEEE
Date: 06-2016
Publisher: IEEE
Date: 06-2018
Publisher: IEEE
Date: 06-2018
Publisher: AIP Publishing
Date: 06-02-2018
DOI: 10.1063/1.5000323
Abstract: We explore the influence of interstitial iron (Fei) on lifetime spectroscopy of boron-oxygen (B-O) related degradation in p-type Czochralski silicon. Theoretical and experimental evidence presented in this study indicate that iron-boron pair (Fe-B) related reactions could have influenced several key experimental results used to derive theories on the fundamental properties of the B-O defect. Firstly, the presence of Fei can account for higher apparent capture cross-section ratios (k) of approximately 100 observed in previous studies during early stages of B-O related degradation. Secondly, the association of Fe-B pairs can explain the initial stage of a two-stage recovery of carrier lifetime with dark annealing after partial degradation. Thirdly, Fei can result in high apparent k values after the permanent deactivation of B-O defects. Subsequently, we show that a single k value can describe the recombination properties associated with B-O defects throughout degradation, that the recovery during dark annealing occurs with a single-stage, and both the fast- and slow-stage B-O related degradation can be permanently deactivated during illuminated annealing. Accounting for the recombination activity of Fei provides further evidence that the B-O defect is a single defect, rather than two separate defects normally attributed to fast-forming recombination centers and slow-forming recombination centers. Implications of this finding for the nature of the B-O defect are also discussed.
Publisher: Wiley
Date: 27-07-2021
DOI: 10.1002/PIP.3455
Abstract: Light‐ and elevated temperature‐induced degradation (LeTID) can have significant and long‐lasting effects on silicon photovoltaic modules. Its behaviour is complex, showing highly variable degradation under different conditions or due to minor changes in device fabrication. Here, we show the large difference in LeTID kinetics and extents in multi‐crystalline passivated emitter and rear cell (multi‐PERC) modules from four different manufacturers. Varied accelerated testing conditions are found to impact the maximum extent of degradation in different ways for different manufacturers complicating the ability to develop a universal predictive model for field degradation. Relative changes in the open‐circuit voltage ( V OC ) have previously been used to assess extents of LeTID however, due to the greater impact of the defect at lower injection, the V OC is shown to degrade less than half as much as the voltage at maximum power point ( V MPP ). The MPP current ( I MPP ) and fill factor (FF) also degrade significantly, having an even larger overall impact on the power output. These observations imply that currently employed methodologies for testing LeTID are inadequate, which limits the reliability of future predictive models. In light of this, the field must develop a more holistic approach to analysing LeTID‐impacted modules, which incorporates information about changes under MPP conditions. This will allow for a much clearer understanding of LeTID in the field, which will assist the performance of future PV systems.
Publisher: Wiley
Date: 16-02-2021
Publisher: Elsevier BV
Date: 08-2016
Publisher: AIP Publishing
Date: 2019
DOI: 10.1063/1.5123894
Publisher: Springer Science and Business Media LLC
Date: 19-11-2017
Publisher: Elsevier BV
Date: 2021
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 2019
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 11-2018
Publisher: Wiley
Date: 21-02-2023
DOI: 10.1002/PIP.3687
Abstract: High‐efficiency silicon‐based tandem solar cells will likely drive the push towards terawatt (TW) scale PV manufacturing on the pathway to net zero emissions by 2050. In this work, we provide a comprehensive analysis of material consumption and sustainability issues for future tandem solar cells. First, we analyse the material consumption and sustainable manufacturing capacity of a variety of potential candidates for the top cell in a silicon‐based tandem cell. We show that III‐V, CIGS and CdTe are not suitable to support TW‐scale manufacturing. Perovskites thus present the most sustainable approach, as long as indium is not required in the cell structure. Next, we turn our attention to the silicon bottom cell architecture by comparing PERC, TOPCon and SHJ. Although tandem cells can generally reduce silver consumption relative to single junction silicon cells due to the more favourable J MP / V MP ratio, the PERC cell architecture could allow for significantly reduced Ag consumption compared with both TOPCon and SHJ by relying on Al for the rear p‐type contact. In order to drive a rapid shift towards TW‐scale manufacturing, a rapid upscaling compared with the current production capacity is needed. The results presented herein highlight the need for careful consideration of sustainability issues when designing future high‐efficiency tandem cells that will help the world mitigate the dangers of climate change.
Publisher: Elsevier BV
Date: 12-2017
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 2021
Publisher: IEEE
Date: 06-2018
Publisher: Elsevier BV
Date: 10-2018
Publisher: Wiley
Date: 03-08-2022
Abstract: Herein, the current and future projected polysilicon demand for the photovoltaic (PV) industry toward broad electrification scenarios with 63.4 TW of PV installed by 2050 is studied. The current polysilicon demand by the PV industry in 2021 is equivalent to the consumption of 2.9–3.3 kt GW −1 . Depending on the physical constraints determining the lower limit for future polysilicon consumption, the annual demand can be 6–7 Mt year −1 in 2050 under broad electrification, which requires 10–12 times more of the current production capacity. To achieve broad electrification by 2050, cumulative demand of 46–87 Mt is required. An electricity requirement for purification, ingot pulling, and wafering of ≈360–380 kWh kg −1 for silicon wafers and carbon intensity can lead to a cumulative amount of ≈16.4–58.8 Gt of CO 2‐eq emissions by 2050. To reduce the environmental impact, efficiencies are increased, thinner wafers are used, kerf loss reduced, alternative purification methods with low emission intensities are explored, and opportunities for polysilicon production with decarbonized electricity are explored.
Publisher: Wiley
Date: 14-06-2020
Publisher: Wiley
Date: 06-06-2017
Publisher: Wiley
Date: 21-09-2022
Abstract: The global cumulative photovoltaic (PV) installed capacity is now over 1 TW. While this is an impressive amount of PV growth, it contributes less than 3% of total electricity generation and, therefore, requires significantly more PV to decarbonize the electricity sector completely. In order to achieve this decarbonization sustainably, all factors must be considered, including the extraction and purification of abundant materials. Based on conservative and ambitious future PV production scenarios and learning rate (LR) for material consumption reduction, the material demands for the future are projected. The concept of LR is applied to estimate the reduced material consumption based on the “maturity” of PV technology or the cumulative installed PV capacity. Herein, it is suggested that abundant materials like copper, concrete, and aluminum may face shortages if PV production follows the broad electrification scenario. Steel, in comparison, likely does not encounter any material shortages. Nevertheless, the work here demonstrates that the demand for even abundant materials should be minimized to decarbonize energy usage and mitigate climate change sustainably.
Publisher: Elsevier BV
Date: 08-2016
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 2020
Publisher: IOP Publishing
Date: 08-03-2021
Abstract: In this work, the efficiency potential of the fully screen-printed passivated emitter and rear contact (PERC) solar cell structure is investigated via numerical simulations. A series of improvements and optimizations are performed on bulk quality, emitter properties and metallization of screen-printed PERC solar cells based on experimental results obtained in both industry and laboratory environments. With significantly improved bulk and surface passivation quality, we find that carrier recombination losses at the metal/silicon interface will impose a substantial limitation on efficiencies, highlighting the need for developing new screen-printing technologies to overcome the limitation from contact recombination. By improving the effectiveness of the back-surface field, reducing coverage area of laser-doped selective emitters and the front metal/silicon interface contact area, a 15 mV improvement in open-circuit voltage ( V OC ) was achieved in our modelled cells, due to greatly reduced contact recombination losses. With the further implementation of a multi-busbar and fine-line printing technologies, efficiency above 24% was obtained from simulations. Subsequently, a comprehensive pathway towards 24% efficiency for screen-printed PERC solar cells is proposed, without the need to implement passivated contacts or transition to a plated metallisation scheme. Key target requirements for future developments are also identified.
Publisher: Elsevier BV
Date: 12-2017
Publisher: Wiley
Date: 16-07-2019
Abstract: Herein, low‐cost p‐type upgraded metallurgical‐grade (UMG) multicrystalline silicon wafers are processed from the edge of the silicon cast using a multi‐stage defect‐engineering approach, incorporating gettering and hydrogenation to improve the wafer quality. Significant reductions in the concentration of interstitial iron and improvements in the bulk lifetime from 15 to 130 µs are observed. Subsequently, all the surface layers are removed and silicon heterojunction solar cells are fabricated. The cells exhibit an efficiency of 18.7%, and open‐circuit voltages over 690 mV is formed using wafers with initial lifetimes of µs. This demonstration of such high voltages, the highest recorded for this material to date, indicates the power of the gettering and hydrogenation processes used and the potential of p‐type UMG silicon to fabricate heterojunction solar cells and other solar cell technologies capable of high open‐circuit voltages.
Publisher: Elsevier BV
Date: 10-2021
Publisher: Wiley
Date: 09-12-2019
DOI: 10.1002/PIP.3230
Abstract: In this work, we integrate defect engineering methods of gettering and hydrogenation into silicon heterojunction solar cells fabricated using low‐lifetime commercial‐grade p‐type Czochralski‐grown monocrystalline and high‐performance multicrystalline wafers. We independently assess the impact of gettering on the removal of bulk impurities such as iron as well as the impact of hydrogenation on the passivation of grain boundaries and B‐O defects. Furthermore, we report for the first time the susceptibility of heterojunction devices to light‐ and elevated temperature–induced degradation and investigate the onset of such degradation during device fabrication. Lastly, we demonstrate solar cells with independently verified 1‐sun open‐circuit voltages of 707 and 702 mV on monocrystalline and multicrystalline silicon wafers, respectively, with a starting bulk minority‐carrier lifetime below 40 microseconds. These remarkably high open‐circuit voltages reveal the potential of inexpensive low‐lifetime p‐type silicon wafers for making devices with efficiencies without needing to shift towards n‐type substrates.
Publisher: IEEE
Date: 13-06-2020
Publisher: IEEE
Date: 06-2019
Publisher: IEEE
Date: 06-2019
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 05-2019
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D1EE01814K
Abstract: As the photovoltaic (PV) industry heading towards the multi-TW scale, PV technologies need to be carefully evaluated based on material consumption rather than just efficiency or cost to ensure sustainable growth of the industry.
Publisher: IEEE
Date: 06-2017
Publisher: IOP Publishing
Date: 16-11-2021
Abstract: The wide variety of silicon materials used by various groups to investigate LeTID make it difficult to directly compare the defect concentrations ( N t ) using the typical normalised defect density (NDD) metric. Here, we propose a new formulation for a relative defect concentration ( β ) as a correction for NDD that allows flexibility to perform lifetime analysis at arbitrary injection levels (Δ n ), away from the required ratio between Δ n and the background doping density ( N dop ) for NDD of Δ n/N dop = 0.1. As such, β allows for a meaningful comparison of the maximum degradation extent between different s les in different studies and also gives a more accurate representative value to estimate the defect concentration. It also allows an extraction at the cross-over point in the undesirable presence of iron or flexibility to reduce the impact of modulation in surface passivation. Although the accurate determination of β at a given Δ n requires knowledge of the capture cross-section ratio ( k ), the injection-independent property of the β formulation allows a self-consistent determination of k . Experimental verification is also demonstrated for boron-oxygen related defects and LeTID defects, yielding k -values of 10.6 ± 3.2 and 30.7 ± 4.0, respectively, which are within the ranges reported in the literature. With this, when extracting the defect density at different Δ n ranging between 10 14 cm −3 to 10 15 cm −3 with N dop = 9.1 × 10 15 cm −3 , the error is less than 12% using β , allowing for a greatly improved understanding of the defect concentration in a material.
Publisher: Author(s)
Date: 2018
DOI: 10.1063/1.5049333
Publisher: Elsevier BV
Date: 12-2017
Publisher: Wiley
Date: 19-10-2023
DOI: 10.1002/PIP.3747
Publisher: AIP Publishing
Date: 07-02-2017
DOI: 10.1063/1.4975685
Abstract: The fast and slow boron-oxygen related degradation in p-type Czochralski silicon is often attributed to two separate defects due to the different time constants and the determination of different capture cross section ratios (k). However, a recent study using high lifetime s les demonstrated identical recombination properties for the fast and slow degradation and proposed an alternative hypothesis that these were in fact due to a single defect. The study presented in this article provides further experimental evidence to support the single defect hypothesis. Thermal annealing after light soaking is used to investigate the behaviour of subsequent boron-oxygen related degradation. Modifying the temperature and duration of dark annealing on pre-degraded s les is observed to alter the fraction of fast and slow degradation during subsequent illumination. Dark annealing at 173 °C for 60 s is shown to result in almost all degradation occurring during the fast time-scale, whereas annealing at 155 °C for 7 h causes all degradation to occur during the slow time-scale. This modulation occurs without changing the total extent of degradation or changing the capture cross-section ratio. The results are consistent with the fast decay being caused by defect formation from immediately available defect precursors after dark annealing, whereas the slow degradation is caused by the slow transformation of another species into the defect precursor species before the more rapid reaction of defect formation can proceed.
Publisher: Wiley
Date: 15-12-2022
DOI: 10.1002/PIP.3661
Abstract: The clean energy transition could see the cumulative installed capacity of photovoltaics increase from 1 TW before the end of 2022 to 15–60 TW by 2050, creating a significant silver demand risk. Here, we present a silver learning curve for the photovoltaic industry with a learning rate of 20.3 ± 0.8%. Maintaining business as usual with a dominance of p‐type technology could require over 20% of the current annual silver supply by 2027 and a cumulative 450–520 kt of silver until 2050, approximately 85–98% of the current global silver reserves. A rapid transition to higher efficiency tunnel oxide passivated contact and silicon heterojunction cell technologies in their present silver‐intensive forms could increase and accelerate silver demand. As we approach annual production capacities of over 1 TW by 2030, addressing the silver issue requires increased efforts in research and development to increase the silver learning rate by 30%, with existing silver‐lean and silver‐free metallisation approaches including copper plating and screen‐printing of aluminium and copper.
Publisher: Elsevier BV
Date: 09-2018
Publisher: Elsevier BV
Date: 02-2020
Publisher: Author(s)
Date: 2018
DOI: 10.1063/1.5049329
Publisher: AIP Publishing
Date: 2019
DOI: 10.1063/1.5123882
Publisher: AIP Publishing
Date: 22-02-2021
DOI: 10.1063/5.0036039
Abstract: For the development of photonic integrated circuits, it is mandatory to implement light sources on a Si-on-insulator (SOI) platform. However, point defects in the Si matrix and, e.g., at the Si/SiO2 interface act as nonradiative recombination channels, drastically limiting the performance of Si-based light emitters. In this Letter, we study how these defects can be healed by applying an advanced hydrogenation process, recently developed in photovoltaic research for the passivation of performance-limiting defects in Si solar cells. Upon hydrogenation, we observe an increase in the room temperature photoluminescence (PL) yield by a factor of more than three for defect-enhanced quantum dots (DEQDs) grown on float-zone Si substrates, revealing the potential of this technique to passivate detrimental defects. For DEQDs grown using SOI substrates, the PL yield enhancement even exceeds a factor of four, which we attribute to the additional passivation of defects originating from the substrate. The results for SOI substrates are of particular interest due to their relevance for future photonic integrated circuits.
Publisher: IEEE
Date: 06-2018
Publisher: Author(s)
Date: 2018
DOI: 10.1063/1.5049323
No related grants have been discovered for Moonyong Kim.