The terrestrial photovoltaic market has been growing at an amazing pace during the last two decades with no sign of slowing down. In 2008 alone the global PV production exceeded 7 gigawatts. The major sectors of end-use are solar-powered homes, grid-interactive power, remote power, and communications. The rapid growth has been associated with a steady increase in the production of base semiconductor materials (mainly silicon), development of advanced device manufacturing technologies and back-end electronics for power conditioning.
Over the last three decades several technological advances and large-scale deployment initiatives have helped reduce the cost of PV by more than a factor of 10. While there is still a strong need to further reduce the cost of PV to achieve cost-parity with conventional (fossil fuel-based) electricity, this goal is largely predicted to be within reach. Continued R&D on affordable semiconductor feedstock, electronic materials, and compatible device & module fabrication technologies coupled with a growing PV market are key to making PV an economically viable renewable energy source.
About 87% of the PV cells that are currently produced use wafer-based crystalline silicon as the based semiconductor material. This includes single crystalline, multicrystalline, and Si ribbon materials. This is primarily due to the proven reliability of Si and to the material knowledge & technology originated from the microelectronics industry. The remaining 13% includes thin film PV technologies, principally amorphous Si and other thins films such as copper-indium-gallium-selenide (CIGS), and cadmium telluride (CdTe). Organic PV is also being actively researched.
In addition to the currently industrialized crystalline Si and thin-film PV technologies, a third generation PV based on nanotechnologies has the potential of yielding ultra-high conversion efficiencies thus dramatically reducing the cost per watt. The third-gen technologies, utilizing nano-structures and quantum dots, incorporate new physical mechanisms to enhance the photon capture, carrier generation and carrier collection. Theoretically the third-gen PV technologies can yield conversion efficiencies that are much higher (2 - 3 fold) than the current practical PV devices. The performance of third-gen PV devices are yet to be experimentally demonstrated at the laboratory level, and it is expected that it will only be in the medium-to-long term that these new materials and technologies reach the manufacturing phase.