Recently, Jolywood’s solar cell R&D team achieved a major breakthrough in uncovering the efficiency enhancement mechanism of its proprietary Jolywood Special Injected Metallization (JSIM) technology. The research findings were published in Progress in Photovoltaics: Research and Applications, a leading journal in the solar energy field. The study was a collaborative effort between Jolywood and the School of Photovoltaic and Renewable Energy Engineering at the University of New South Wales (UNSW), validating the ultra-low recombination advantage of JSIM from a theoretical perspective. This publication not only underscores the technological strength of the Jolywood team but also exemplifies the company’s unwavering commitment to innovation, providing strong momentum for its sustainable growth.

JSIM technology adopts an advanced low-line-resistance electrode paste system, combined with a high-energy injection firing process that facilitates excellent ohmic contact and reduces metal-induced recombination. The reformulated paste system also resolves the damp-heat reliability challenges faced by conventional TOPCon cells—a result previously reported in earlier publications. Meanwhile, the integration of JSIM has significantly improved solar cell efficiency. In response, the Jolywood–UNSW joint team has launched an in-depth investigation into the underlying mechanisms behind this performance enhancement.

Due to the unique firing process involved in JSIM, both-sides screen-printed electrodes are required to establish current conduction via injected-induced current paths, making it difficult to characterize metal contact recombination. To overcome this challenge, the researchers innovatively designed independent metal contact unit patterns with varying electrode coverage ratios. By Quokka 3, they successfully extracted front and rear metal contact recombination parameters for JSIM cells—values significantly lower than those in conventionally sintered TOPCon cells. Further loss analysis confirmed that this substantial reduction in contact recombination is the primary contributor of the notable efficiency gains.

The Main Takeaways

1. Cell Efficiency improvements

The comparison of I-V characteristics between JSIM and standard TOPCon cells (labeled as “BL” in figures) reveals comprehensive improvements across key performance parameters. Notably, the power conversion efficiency of JSIM cells increased by 0.58%_abs. This improvement primarily stems from an enhanced open-circuit voltage (Voc), which rose by more than 11 mV compared to conventional TOPCon counterparts. Additionally, thanks to the adoption of a high sheet-resistance, uniform emitter, JSIM cells exhibit reduced blue-light absorption losses associated with the laser-defined selective heavily-doped regions of standard TOPCon structures, contributing to an increase in short-circuit current density (Jsc).

2. Reduced Metal-Induced Recombination

As contact area increases, both JSIM and conventional TOPCon cells exhibit a near-linear decline in Voc. However, extracted recombination parameters reveal that JSIM cells achieve significantly lower metal-induced recombination levels:

·J₀,front-met: 88 fA/cm² (vs. 280 fA/cm² for standard TOPCon)

·J₀,rear-met: 21 fA/cm² (vs. 98 fA/cm² for standard TOPCon)

These reductions translate into an estimated 9.37 mV Voc improvement and 0.36%_abs increase in fill factor (FF), contributing a total efficiency gains of 0.42%_abs. Although contact resistance in JSIM is slightly higher than BL, the combination of ultra-low recombination and reduced line resistance still leads to a net FF improvement of 0.1%_abs. Simulations indicate that JSIM offers a theoretical efficiency gain potential of up to 0.61%_abs.

3. Substantial Potential for Further Optimization

Power loss analysis reveals different loss mechanisms between the two cell types. In conventional TOPCon cells, front and rear surface recombination are the largest losses. In JSIM cells, losses predominantly stem from intrinsic and extrinsic recombination, emitter-side non-contact recombination, and horizontal carrier transport limitations due to high sheet resistance.

The study identifies several pathways for further performance enhancement in JSIM cells, including:

·Using high-resistivity wafers to reduce recombination,

·Enhancing surface passivation quality,

·Optimizing the balance between sheet resistance and contact resistance,

·Narrowing grid lines through ultra-fine metallization design.

Collectively, these strategies could unlock an additional ~0.3%_abs in efficiency improvements.

Product Quality and Technological Innovation are the Cornerstones of Jolywood

As one of the first enterprises to mass produce TOPCon products, Jolywood has remained firmly committed to R&D and continuous technological iteration. Beyond the ultra-low recombination JSIM innovation, the company has introduced several other advanced technologies:

·Enhanced Safety: The POPAID technology eliminates wrap-round, significantly reducing reverse leakage risks during power generation.

·Superior Aesthetics: A multi-layer coating process achieves a uniform full-black appearance, setting a new standard for color uniformity in solar cells.

“Innovation is the primary driving force.” The publication of this joint research with UNSW not only highlights Jolywood’s strength in independent R&D but also signals its determination to lead the photovoltaic industry through technological leadership. Looking ahead, Jolywood will continue strengthen its investment in innovation, delivering high-efficiency and highly reliable solar solutions to the global market.