Modeling the cooperative energy transfer dynamics of quantum cutting for solar cells

Abstract

Cooperative energy transfer (ET) is a quantum cutting (or downconversion) process where a luminescent center splits its excited state energy in two by simultaneous transfer to two nearby acceptor centers, thus yielding two low-energy photons for each high-energy photon absorbed. It has the potential to greatly enhance the efficiency of phosphors for lighting or the UV/blue response of next generation photovoltaics. Many pairs of luminescent centers have been claimed to enable quantum cutting by cooperative ET. However, direct proof that the ET mechanism is cooperative is often lacking. Here we present a model that can be used to fit or predict the dynamics of cooperative ET in codoped crystals, as a function of the concentration of acceptor centers. It also yields an analytical expression for the efficiency of cooperative ET. Our model can be used to provide evidence for quantum cutting materials, quantify the ET parameter(s), and optimize the doping concentration.