Henning Sirringhaus reviews the progress of organic field-effect transistors (OFETs) over the past 25 years, highlighting significant improvements in materials performance, with field-effect mobilities exceeding 1 cm² V⁻¹ s⁻¹, surpassing those of amorphous silicon-based devices. The article discusses the development of small-molecule and conjugated polymer materials for OFETs, focusing on their charge transport physics and potential for further performance improvements. It also addresses the challenges in extracting accurate mobility values from device characteristics and the importance of understanding transport mechanisms for future applications. The review emphasizes the need for materials that can meet the demanding performance requirements of flexible organic light-emitting diode (OLED) displays, particularly for active-matrix addressing. Recent advances in materials, such as high-performance conjugated polymers and small-molecule semiconductors, are highlighted, along with their potential for enabling next-generation applications. The article also discusses the importance of device stability and uniformity, as well as the role of structural and energetic disorder in charge transport. The review concludes with an outlook on the future of OFETs, emphasizing their potential to enable new scientific opportunities and applications in flexible electronics.Henning Sirringhaus reviews the progress of organic field-effect transistors (OFETs) over the past 25 years, highlighting significant improvements in materials performance, with field-effect mobilities exceeding 1 cm² V⁻¹ s⁻¹, surpassing those of amorphous silicon-based devices. The article discusses the development of small-molecule and conjugated polymer materials for OFETs, focusing on their charge transport physics and potential for further performance improvements. It also addresses the challenges in extracting accurate mobility values from device characteristics and the importance of understanding transport mechanisms for future applications. The review emphasizes the need for materials that can meet the demanding performance requirements of flexible organic light-emitting diode (OLED) displays, particularly for active-matrix addressing. Recent advances in materials, such as high-performance conjugated polymers and small-molecule semiconductors, are highlighted, along with their potential for enabling next-generation applications. The article also discusses the importance of device stability and uniformity, as well as the role of structural and energetic disorder in charge transport. The review concludes with an outlook on the future of OFETs, emphasizing their potential to enable new scientific opportunities and applications in flexible electronics.