Figure 3: Device energy band diagram under different conditions.
From: Quantitative o perando visualization of the energy band depth profile in solar cells
(a) VL alignment of an ITO/MoOx/P3HT:PCBM/LiF/Al BHJ device before contact; (b) Fermi-level alignment after contact in the dark; (c) separated quasi-Fermi levels for electrons and holes under illumination; and (d) separated quasi-Fermi levels due to bias voltages between the two electrodes. Here, HOMO means highest occupied molecular orbital and LUMO means lowest unoccupied molecular orbital.
