Scientists have developed a novel manufacturing process that enables the production of high-efficiency solar panels with increased power output without significantly raising manufacturing complexity or costs.
This innovative approach combines a specially formulated silver paste with laser treatment to enhance a type of solar cell called a tunnel oxide passivated contact (TOPCon) cell. The improved device achieved a certified power conversion efficiency of 26.31%, ranking it among the top-performing TOPCon solar cells to date.
The project was led by Professor Ye Jichun’s team at the Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences. Collaborating with researchers and industry partners from Soochow University, Zhejiang Gonda Electronic Technology, and JA Solar Technology, the team published their findings in the journal Matter.
Crystalline silicon solar cells are currently the leading technology in the solar industry, with TOPCon technology gaining popularity because it is compatible with existing manufacturing equipment and processes used for traditional silicon cells. However, creating metal electrical contacts on TOPCon cells presents a significant challenge.
Typically, manufacturers print a silver-aluminum paste onto the cell and then heat it to ensure a good electrical connection for current flow. This process, however, can harm the cell’s sensitive surface layers, which are crucial for minimizing energy loss. Additionally, the heat causes the metal lines to widen, casting more shadow and reducing the sunlight reaching the active area.
The researchers addressed these issues by developing a new approach. They first created an aluminum-free silver paste that maintains its shape after printing, allowing for taller and narrower metal lines. These gridlines have an aspect ratio of 55%, balancing electrical conductivity with minimal shading to maximize sunlight absorption.
Next, they integrated the paste with a technique called laser-enhanced contact optimization (LECO). This involves scanning a laser along the metal gridlines while applying an electrical voltage, producing highly localized heating. This process establishes solid electrical contacts at specific points while minimizing heat exposure elsewhere.
By concentrating heat only where needed, the method reduces damage to the solar cell’s protective surface layers compared to traditional high-temperature techniques. The combined process yielded impressive results: the completed TOPCon cells achieved a certified efficiency of 26.31% and a high short-circuit current density of 41.98 mA/cm², the highest recorded for large-area TOPCon cells.
This advancement holds significant promise for the solar industry. It offers a way to obtain reliable electrical contacts without compromising the cell’s protective features. Furthermore, the method is designed to be scalable, providing a practical pathway for manufacturing more efficient commercial solar panels and increasing electricity production from the same amount of sunlight.