Hot-carrier solar cell spectral insensitivity: Why develop the hot-carrier solar cell when we have multi-junction devices

The hot carrier solar cell (HCSC) offers one route to high efficiency solar energy conversion and has similar fundamental limiting efficiency to multi-junction (MJ) solar cells however, the HCSC is at a much earlier stage of development. We discuss the unique features of the HCSC which distinguish it from other PV technologies, providing motivation for development. We consider the potential for a low concentration hot-carrier enhanced single-junction solar cell, enabled by field enhancing cell architectures. To support this we experimentally show that changing sample geometry to increase carrier density, while keeping phononic and electronic properties constant, substantially reduces hot-carrier themalization coefficient. Such a scheme might have similar applications to todays high efficiency single-junction devices while allowing from some intrinsic efficiency enhancement. We also use spectral data simulated using SMARTS to identify HCSC spectral insensitivity relative to MJ devices. Spectral insensitivity increases annual energy yield relative to laboratory test efficiency, reducing the cost of PV power generation. There are also several practical advantages: a single device design will operate optimally in a variety of locations and solar power stations are less reliant of accurate, long-range atmospheric simulation to achieve energy yield targets.