Solar energy, as a clean and renewable resource, plays a pivotal role in advancing sustainable energy technologies. The efficiency of front-side silver paste is critical for the photovoltaic performance of Tunnel Oxide Passivated Contact (TOPCon) solar cells. In this study, we comprehensively investigated how the composition of organic vehicles in conductive pastes influences both printing rheological properties and electrical performance. Through rheological characterization, contact angle measurements, and Three-Interval Thixotropy Tests (3ITT), we examined the effects of varying solvent, binder, and thixotropic agent ratios on paste properties. The optimized formulation—a solvent mixture of lauryl alcohol ester (TE), butyl carbitol (DGME), butyl carbitol acetate (BCA), and dibutyl phthalate (DBP) in a 3:4:2:1 ratio, with ethyl cellulose (EC) STD10 as the binder and a polyamide wax (PAW)–hydrogenated castor oil (HCO) thixotropic agent at a 3:1 mass ratio—demonstrated superior viscosity control and rapid structural recovery. Printed grid lines achieved a height-to-width ratio (H/W) of 0.35 and a sheet resistance (Rs) of 1.43 Ω/□. These findings reveal direct relationships between organic vehicle composition, paste rheology, and functional performance, providing practical guidance for the design and optimization of high-performance conductive pastes for c-Si solar cells. This work establishes a foundation for improving both the efficiency and reliability of next-generation silver paste formulations in photovoltaic applications.

Micron-sized spherical gold powders possessing high dispersibility and favorable sintering performance are critical for high-performance thick-film gold conductor pastes. Herein, monodisperse micron-sized spherical gold powders were fabricated through an environmentally benign chemical reduction route, where L-ascorbic acid served as the reductant and gum arabic acted as the dispersant. The influences of solution pH, reaction temperature, stirring speed and reaction time on particle morphology and size distribution were systematically explored. With the mass ratio of gold precursor to reductant maintained at 1:1, the optimal synthetic conditions were determined as pH 3, 20 °C, 550 rpm and 20 min. Under such optimized conditions, spherical gold particles with an average diameter of 0.88 μm were harvested, featuring narrow particle-size distribution, high sphericity, good dispersibility and low organic residue of 0.70 wt%. The as-prepared powder delivered high crystallinity and appropriate sintering activity. Quantitative porosity characterization demonstrated that the thick film derived from this micron-scale gold powder achieved the minimum residual porosity in comparison with the other two counterparts, verifying its outstanding densification behavior. Benefiting from the well-developed dense conductive network, the resultant thick film achieved a low sheet resistance of 1.73 mΩ/sq, a superior adhesion strength of 3.65 N/mm², as well as reliable multi-firing stability. This work offers a feasible approach for large-scale manufacturing of high-quality gold powders toward thick-film electronic devices.

High-reliability thick-film gold conductor pastes serve as core functional materials for high-end electronic packaging. Traditional lead-containing glass binders suffer from environmental toxicity, restricting their large-scale green applications. Herein, a series of Bi₂O₃–B₂O₃–TeO₂ lead-free glasses with tunable Bi₂O₃/B₂O₃ ratios was prepared to explore the regulation of glass composition in the intrinsic structure, thermal behavior and sintering performance of gold thick films. The Bi₂O₃/B₂O₃ ratio strongly influences melt flow: excessive Bi₂O₃ induces local segregation of the glass phase, while surplus B₂O₃ weakens wettability and pore-filling capacity. Optimized A3 glass achieves synergy between glass flow and sintering kinetics of gold particles. The resulting P3 film has porosity of 3.12%, sheet resistance of 2.92 mΩ/sq and interfacial adhesion of 3.78 N/mm². Its sheet resistance variations remain merely +0.96% and −1.02% after two refiring cycles, delivering good conductivity, strong interfacial bonding and stable electrical behavior upon refiring. This work offers experimental support for compositional design of lead-free glass binders for gold conductor pastes.