Theoretical modeling on luminescent down-shifting process: A Discussion on luminescent molecule design

A model was developed to describe the luminescent down-shifting (LDS) process in photovoltaic application. The model links the J_sc enhancement (J_LDS%) of the solar cell to the photophysical properties including absorption (λ_abs) and emission (λ_em) wavelengths, Stokes shift (Δλ) and spectral cutting point (λ_SCP), as well as fluorescence quantum yield (Φ_f), of the luminescent molecules. It suggests that Φ_f is a more crucial parameter than λ_abs and λ_em. It also suggests that λ_SCP is a better parameter than Δλ on describing J_LDS%. The model is tested with luminescent molecules and the results are consistent with the experimental results.