David Ferry1
Arizona State Univ1
Hot carrier solar cells were first proposed many decades ago. Over the intervening years, there has been a continuing quest to create these cells which hold promise to shatter the Shockley-Queisser efficiency limit on single-junction solar cells. While there have been many positive and suggestive results in recent years, there remains no true operational hot carrier solar cell. There are perhaps many reasons for this state. Here, many of the requirements for achieving such a hot carrier solar cell will be discussed and some approaches modernized in terms of their science. These will be discussed in terms of Valley photovoltaics, in which carriers are transferred to higher lying valleys of the conduction band. This approach has similarities to intermediate-band cells, and these will be pointed. Topics will include the valley photovoltaics approach, power versus efficiency, expectations for these cells, energy selective barriers, and non-equilibrium phonons