Category: Solar Cell Materials

Lanthanides for UC Devices

An alternative group of materials that give long-lived intermediate states are those based on the lanthanide (or rare-earth) group of elements, because of their narrow and suitably spaced energy transitions. The lanthanides have a valence shell of 4f electrons that are shielded by full outer 6s and 5p shells. Hence, their electronic transitions tend to […]

Reverse Auger Generation

An alternative approach is to absorb a short-wavelength photon high up in the conduction band of various semiconductors. There is then the possibility of an impact ionisation event (i. e. reverse Auger recombination) in which the high-energy electron excites an additional electron to the conduction band, thus creating two or more electron-hole pairs at the […]

Lanthanide-Based DC

Praseodymium (Pr3 +) is a good choice because of its widely dispersed energy levels well matched for photon cutting, [Dieke, 1968], see Figure 9.10. The 3P2, % and P0 levels at between 440 and 490 nm can absorb blue photons that can then radiatively recombine via the :G4 level at 1010 nm – at just […]

Downconversion, QE > 1

A downconverting device (DC) must be placed in front of a standard cell and can boost current by converting a UV photon to more than one photon just above the bandgap of the solar cell – thus boosting the current. However, the DC does require that more lower-energy photons are emitted than high-energy photons absorbed, […]