Ytterbium sensitization in KY3F10: Pr3+, Yb3+ for silicon solar cells efficiency enhancement

The codoping of KY3F10 with Pr3+ and Yb3+ ions is investigated as a possible quantum cutting system to enhance solar cells efficiency. For one visible photon absorbed by Pr ions, two ytterbium ions are expected to be excited by two consecutive energy transfers. The subsequent emission of two infrared photons reduces thus the thermalization losses usually observed in Si solar cells. Emission spectra and lifetime decays in KY3F10 doped with 0.5% Pr3+ and codoped with 0%, 1%, 10% and 20% Yb3+ show an increase of the energy transfer efficiency from Pr3+ to Yb3+ with the Yb3+ concentration. For the first Pr3+ to Yb3+ energy transfer, an efficiency close to 100% is achieved in KY3F10: 0.5%Pr3+, 20%Yb3+. However, this promising result faces challenging issues since an increase in Yb concentration induces energy migration between Yb3+ ions which impairs the Yb3+ luminescence.