Researchers have discovered that an exotic form of silicon may improve solar cell efficiency. This predicted improvement using a structure of silicon called silicon BC8 was detailed in the January edition of the journal Physical Review Letters, and is based upon computer simulations by researchers at the University of California Davis and in Hungary.
Scientists rejected the conventional one electron-hole pairing per incoming photon, which typically has a maximum efficiency of 33%. Nanoparticles of conventional silicon only work in ultraviolet light under quantum confinement.
Quantum confinement is responsible for generating more than one electron-hole pair, and scientists at the Los Alamos National Laboratory, UC Davis, and the National Renewable Energy Laboratory are currently exploring this phenomenon in greater detail.
Scientists have discovered that generating more than one electron-hole pair per photon leads to a maximum efficiency of 42% – a level far beyond any solar cell currently available. The new approach also works in visible sunlight, not just ultraviolet light.
Experts also believe that by pairing the multiple electron-hole per photon with parabolic mirrors, the maximum efficiency might rise to 70%.
The researchers simulated the behavior of a structure of silicon called silicon BC8. BC8 is formed under high pressure but is stable at normal pressures. Simulations were run through the National Energy Research Scientific Supercomputing Center at the Lawrence Berkeley Laboratory, which granted the project 10 million hours of supercomputer time.
The results? Nanoparticles of silicon BC8 do, in fact, generate multiple electron-hole pairs per photon even when exposed to visible light, and scientists are excited about the possibilities of creating the world’s most efficient solar cell.