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A series of novel dialkyl disulfonate gemini surfactants (2C n -SCT where n is the carbon number of the hydrophobic chain) were synthesized from cyanuric chloride, aliphatic amine and taurine. The chemical structures of the prepared compounds were confirmed by 1 H NMR, 13 C NMR, IR spectra, and ESI-MS. Their critical micelle concentrations (CMC) in the aqueous solutions at 25°C were determined by surface tension and electrical conductivity methods. With the increasing length of the carbon chain, the values of their CMC initially decreased, and then increased with an alkyl chain length of 14. The surface tension measurements of 2C n -SCT (except for n = 14) determined that there is a low CMC, a great efficiency in lowering the surface tension, and a strong adsorption at the air-water interface. In addition, adsorption and micellization behavior of 2C n -SCT were estimated from pC 20 , the minimum average area per surfactant molecule (A min ), and standard free energy micellization and adsorption (DG mic and DG ads ). These properties are significantly influenced by the chain length n, and the adsorption is promoted more than the micellization.

LONGi Solar Energy Technology Co. Ltd. has achieved 23.83% for a commercial ptype Cz PERC cell. From a batch of over 40 000 cells, the average line efficiency achieved was 22.5%. R&D studies investigating hydrogenation and degradation show the importance of hydrogenation processes for efficiency improvements and controlling the hydrogen to prevent light-induced degradation. Such degradation is shown to appear very differently under different illumination and temperature conditions. This degradation impacts V OC , I SC , and especially fill factor. Current injection and thermal anneal can be used to recover the degradation, but the recovery may not be stable. Reducing the hydrogen content within the cell is shown to minimise degradation without sacrificing performance, provided that enough hydrogen is retained to passivate boron-oxygen defects. 1 | INTRODUCTION The advanced hydrogenation technology developed at University of New South Wales (UNSW) Sydney is focused on controlling the hydrogen in silicon solar cells to enable enhanced bulk defect passivation and minimise light-induced degradation (LID). 1 Typically studied on lab produced samples and cells, this work with LONGi Solar Energy Technology Co., Ltd. investigates the advanced hydrogenation technology on LONGi's high efficiency p-type Cz commercial cells. LONGi focuses on the R&D, production and sales of monocrystalline silicon wafers, and cells and modules, and at present (Q1, 2019), has 5.5 GW cell and 6.5 GW module capacities. LONGi has always attached great importance to R&D. The cost of R&D investment in the last 5 years has reached 2.38 billion Chinese RMB. The cell R&D department has always been committed to the research and development of high-efficiency monocrystalline solar cell technology. Among them, Cz PERC cells have repeatedly broken the world record; here, LONGi has achieved an efficiency of 23.83%. This cell performance is already almost equal to a 2017 forecasted industrial efficiency prediction of 24% 2 and on the path towards commercial implementation of the 25% efficient PERL lab cell of 1999. 3 LONGi has a long-term partnership with the UNSW Sydney and has in-depth collaborative research on advanced hydrogen passivation technologies to improve the performance and long-term stability of silicon solar cells. 1 In Cz silicon material, hydrogenation is very effective for passivating boron-oxygen(BO) defects that otherwise cause LID. 4,5 The BO defect system can be understood using a three-state model of (1) defect precursors, that under light form (2) active BO defects, and can be passivated by hydrogen to form (3) passivated BO defects. 6,7 More recently, there has been a phenomenon of a new LID caused by hydrogen, which is commonly referred to as light and elevated temperature-induced degradation (LeTID), 8,9 but perhaps more Stuart Wenham equally contributed to this work.

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