CIGS Thin Film Solar Cells

Introduction
More energy from sunlight hits the earth’s surface in one hour than all the energy consumed by humanity in one year. Energy production from sunlight, either through photovoltaics or from solar-thermal electrical energy, would be a clean and plentiful source of green energy. Solar-based electrical energy generation has been around since the 1960s, but has not achieved the efficiency and cost levels required to gain mainstream acceptance. However, research and development in this and other renewable energy areas has increased dramatically on account of the world’s recent attention on global warming and reduction of fossil fuel dependency. As a result, even with limited efficiency, the solar energy market has grown 40% in the last five years and continued growth rates of over 30% annually are predicted in the coming years. The prospect of developing low cost, higher efficiency solar cells to convert sunlight directly into clean electricity and ultimately reduce utility costs on new fossil fuel power plants is the driving focus for the emerging solar industry.

Challenge
While massive government subsidies are currently available, solar growth will be held back unless true economic viability is achieved. The current cost per installed peak watt of $6-$10 is the single largest barrier to widespread adoption. Cost levels must be brought below $3 per installed peak watt, according to industry analysts. The high cost of siliconÑcurrently used in 98% of all solar cells, is a primary reason for not being able to achieve this cost level. Additionally, the high demand of the ever-growing semi-conductor industry will continue to affect silicon availability and pricing. Due to these factors, technology development in solar energy is moving from a focus on silicon to experimentation with other platforms, most notably those using thin-films and nanomaterials.

Solution
Thin film materials can be one-tenth the cost of silicon and in theory could be more efficient. Among thin-film approaches, one of the most promising uses a selenized copper/indium/gallium alloy (CIG). According to NREL, efforts utilizing this CIG alloy compound have been able to demonstrate efficiency levels in small cells that could translate to $1-$5 per installed peak watt. However, current production methods using micron sized particles, or sputtering, have not demonstrated the required uniformity and yield levels for mass quantities. QSI-Nano® metals and alloys can help resolve these challenges. QSI’s nanoscale version of the alloy – dispersed into a paste and offered as a turn-key solution to the solar industry – could potentially enable cost levels to fall well below $3/Wp in full-sized panels and ultimately get below $1/Wp going forward with economies of scale. The small uniform size and high surface energy of QSI’s nanomaterials could help enable ultra-thin and highly uniform films that directly lead to greater manufacturability and increased efficiencies.

QSI’s patented gas phase condensation process (GPC) is capable of producing high purity, narrow distribution nanoscale CIG alloy material in the quantities necessary to support large-scale manufacturing of thin film solar cells. University-based research is currently underway to demonstrate the alloy’s performance, and preliminary results are extremely positive. Once this validation is complete, QSI’s CIG alloy will have the potential to revolutionize solar cell manufacturing by enabling lower production costs and dramatically increased performance, thus finally making thin film solar cells the true energy choice for consumers globally.