As the cornerstone of photovoltaitics industry, silicon solar cell draws extensive interests and its progress on conversion efficiency concerns the implementation of carbon neutrality promise. In order to achieve high efficiency, good surface passivation, low contact resistance and transparent front skin are the indispensable requirements, bringing about variety of technologies and strategies to balance out for maximum efficiency. Recently, our group achieved a new world record, 26.81%, in silicon solar cells using improved heterojunction technology (SHJ). Thanks to the successful integration of nanocrystalline doped hydrogenated silicon (nc-Si:H), surface passivation quality is further enhanced by field effect and the contact resistance is highly restrained. On the other hand, oxygen doping at front nc-Si:H broadens the band gap and the transparency to short-wavelength sunlight is increased for higher short-circuit current density. Combined with new transparent conductive oxide and advanced metallization, intrinsic properties of silicon emerge from intricate power loss mechanism, causing unprecedented fill factor and record conversion efficiency in silicon solar cells. Moreover, our record solar cell is based on front and rear contacted architecture with full-size commercial Czochralski silicon wafer and total-area certification. With the simplicity and compatibility of our SHJ technology to mass production, it is easy to transfer the result into industrial manufacture with high mass production cell conversion efficiency.
The development of high efficiency Si solar cells is seeing successful industrialization of carrier-selective and passivating contact technologies, including Tunnel Oxide Passivated Contact (TOPCon) and Silicon Heterojunction Technology (SHJ). Driven by cell technology innovation, the Si PV industry is making bold moves to see 26-27% efficiencies in mass production in the coming years. Undisputablly, Si wafer development provides strong support for the fast-upgrading cell technologies, and guarantees the technologies' deployment at affordable costs. To date, p-type Si wafer is dominating the market by 95% market share. However, a 5% to 50% uptaking of n-type Si wafer is predicted by ITRPV. One critical factor for this judgement is that the n-type Si solar cell efficiencies are leading ahead that of the p-type. It is well argued that the n-type Si wafer manufacturing can steadily ramp up given the demand, and the cost disadvantage can be alleviated to some extent with scaled production capacity. At the same time, the industry shall not ignore the inherent cost advantage of p-type wafers, and keep exploiting the possibilities to push up the p-type Si solar cell efficiency. In this work, we demonstrate that the p-type SHJ solar cell efficiency can reach 26.6%, which is just 0.2% behind of its n-type counterpart. This result establishes a solid foundation for further SHJ technology development on a cost-effective basis.
A simple self-powered drug delivery system was developed based on the galvanic cell mechanism, involving the direct deposition of a drug-contained polypyrrole (PPy) film on the one side of a titanium foil. After covering the other side with a eicosane-poly(l-lactide) (PLLA) blend film, it is interesting to observe that massive drug release only occurred when the release medium was heated to the body temperature. The methyltetrazolium (MTT) assay indicated that the system had good biocompatibility. Since titanium is one of the most commonly used load-bearing implant materials, it is expected that the present drug delivery system can find applications in titanium-related orthopaedic fields.
Abstract Fully non‐fused ring acceptor (FNFRA) are potentially important for boosting the performance and lowering the material costs of organic solar cells (OSCs). Despite their potential, FNFRA‐based OSCs have not yet matched the performance of their fused ring and partial non‐fused ring counterparts due to limited molecular engineering research. In this work, by incorporating a synergistic strategy of tailoring the β ‐side chain and end‐group of FNFRA with the cyclic “belt” simultaneously, a FNFRA named C6FT‐2F2Cl is constructed. Compared with other symmetric FNFRAs, C6FT‐2F2Cl features a shorter π–π stacking distance and an efficient zigzag charge transport channel, leading to enhanced and balanced charge carrier mobilities, lower non‐radiative energy loss and a higher short‐circuit current density. The power conversion efficiency (PCE) of the C6FT‐2F2Cl‐based OSC reached 13.19%, which is among the best in FNFRA‐based devices. This work provides new valuable insights for the charge transport mechanism associated FNFRAs and paves a new route to the materials design toward high‐performance and low‐cost OSCs.
Though thin film silicon has evolved into an important technology for photovoltaic industry, further increasing its conversion efficiency remains to be a key task. In this work, we report the progress we have made in developing compatible nanocrystalline Si (nc-Si) technology with our existing amorphous silicon germanium (a-SiGe) based multi-junction solar cell manufacturing lines. We have conducted experiments mainly on two types of nc-Si based solar cell structures, a-Si/a-SiGe/nc-Si triple-junction and a-Si/nc-Si double-junction device. Currently we are attaining initial total area efficiency of 10.7% and 12.4% for the triple- and double-junction structures, respectively, on substrate size of 0.79 m 2 (1.245m × 0.635m). Experimental results including study of crystalline volume fraction along nc-Si growth, individual component cell optimization and current match, development of superior tunnel-junction and contact layers are presented.
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