The trick lies in IBM’s ability to cool the tiny solar cell. Concentrating the equivalent of 2,000 suns on such a small area generates enough heat to melt stainless steel, something the researchers experienced first hand in their experiments. But by borrowing innovations from its own research and development in cooling computer chips, the team was able to cool the solar cell from greater than 1,600 degrees Celsius to just 85 degrees Celsius.
The initial results of this project were presented at the 33rd IEEE Photovoltaic Specialists conference last week, where the IBM researchers explained in detail how their liquid metal cooling interface is able to transfer heat from the solar cell to a copper cooling plate much more efficiently than anything else available today.
The IBM research team developed a system that achieved promising results by coupling a commercial solar cell to an advanced IBM liquid metal thermal cooling system using methods developed for the microprocessor industry.
Specifically, the IBM team used a very thin layer of a liquid metal made of a gallium and indium compound that they applied between the chip and a cooling block. Such layers, called thermal interface layers, transfer the heat from the chip to the cooling block so that the chip temperature can be kept low. The company says that its liquid metal solution offers the best thermal performance available today, at low costs, and the technology was successfully developed by IBM to cool high power computer chips earlier.
While concentrator-based photovoltaics technologies have been around since the 1970s, they have received renewed interest in recent times. With very high concentrations, they have the potential to offer the lowest-cost solar electricity for large-scale power generation, provided the temperature of the cells can be kept low, and cheap and efficient optics can be developed for concentrating the light to very high levels.
IBM is exploring four main areas of photovoltaic research: using current technologies to develop cheaper and more efficient silicon solar cells, developing new solution-processed thin-film photovoltaic devices, concentrator photovoltaics and future generation photovoltaic architectures based upon nanostructures such as semiconductor quantum dots and nanowires.
The goal of the projects is to develop efficient photovoltaic structures that would reduce the cost, minimize the complexity and improve the flexibility of producing solar electric power.