Award for groundbreaking studies in the electronic properties of organic semiconductors, particularly the roles of electron spin in the operation of solar cells
Winton Advanced Research Fellow, Akshay Rao was awarded by the Institute of Physics the Henry Moseley Award and Prize for his pivotal research in the field of organic semiconductors and the role of spin in the operation of solar cells.
Rao’s principal concern has been the fission of a spin-singlet photoexcitation in an organic semiconductor into a pair of spin-triplet excitons. This process is spin-allowed and energetically allowed when the exchange matches half of the singlet energy, as found in materials including pentacene.
Rao showed this process can be very fast and efficient, that the triplet exciton can be ionised to an electron–hole pair at a suitable heterojunction, and that the triplet exciton can be rapidly tunnelled into an inorganic semiconductor. He further showed how this process of fission couples coherently with vibrational coordinates. This has established the scope to use this process of exciton doubling to couple to practical solar cells, and may be able to deliver tandem-cell performance in a cheap single-junction cell.