Directing the film structure of organic semiconductors via post-deposition processing for transistor and solar cell applications

The morphology of thin films of molecular and polymeric semiconductors, which is structurally complex and heterogeneous across multiple length scales, is known to significantly affect the device performance. Yet, controlling the film structure is challenging, typically requiring chemical modification of the organic semiconductors, substrates, or the conditions under which the films are formed. Post-deposition processing offers an opportunity to decouple film formation from structural development, providing greater control over molecular ordering in organic semiconductor thin films. This review highlights recent advances in post-deposition processing, focusing specifically on methods that control three important aspects of the film structure - the in-plane and out-of-plane molecular orientations and molecular packing - and correlating these structural changes with device performance in organic thin-film transistors and solar cells. Post-deposition processing methods offer means to control the structure of organic semiconductor thin films across various length scales.