Energy Level Alignment and Sub‐Bandgap Charge Generation in Polymer:Fullerene Bulk Heterojunction Solar Cells (Adv. Mater. 17/2013)

A novel technique – charge modulated electro-absorption spectroscopy (CEMAS) – is reported by Franky So and co-workers on page 2434 and used to determine the energy-level alignment and the effective bandgap of organic heterojunctions. What makes CMEAS unique is that it can directly determine the interface energetics of donor–acceptor blends, not possible using conventional electro-chemical methods.