Electron Lifetime of Over One Month in Disordered Organic Solid-State Films

Understanding intrinsic carrier lifetime in disordered organic solid-state semiconductors is essential for improving device performance in not only molecule-based optoelectronic devices such as organic solar cells (OSC) but also photocatalysts used for producing solar fuel cells. Carriers in disordered films are generally thought to have short lifetimes on a scale ranging from nanoseconds to milliseconds. These short carrier lifetimes cause loss of charges in OSCs and low quantum yields in photocatalysts and impede the future application of organic semiconductors to, for example, charge-storage-based memory devices. This study reports an ultralong intrinsic carrier lifetime of more than one month in a disordered film of an organic semiconductor stored at room temperature without external power. This extraordinary lifetime, which is several orders of magnitude longer than that generally believed possible in conventional organic semiconductors, arises from carrier stabilization by spontaneous orientation polarization, excited spin-triplet recycling, and blocking of recombination processes in disordered films.