Inorganic chemistry: Making iron glow.

Abstract

An iron complex has been made that has a long-lived excited state and emits light at room temperature as a result of a charge-transfer process. This breakthrough might allow the production of cheap solar cells. See Letter p.695 Transition-metal complexes are used as photosensitizers and photocatalysts, and in light-emitting devices. For these uses, the complexes need to be excited from their ground state to a charge-transfer state, which generally needs to be long-lived to ensure efficient performance. This has made it challenging to replace the scarce but high-performing precious metals used in these complexes with Earth-abundant metals that are cheaper and less toxic. Pavel Chabera et al. now show that a design strategy that utilizes ligands with superior electronic properties yields iron complexes with unprecedented long-lived charge-transfer states. With further development, the approach could deliver iron-based materials for use as light emitters and photosensitizers in solar energy devices.