Internal Electric Field on Steering Charge Migration: Modulations, Determinations and Energy‐Related Applications

Abstract Energy‐related problems induced by ever‐continuous fossil consumption have arisen as one of the most challenging issues in the 21 st century, imposing urgent demands on advanced materials to achieve high energy utilization and a sustainable society. In various solar energy utilization and solar‐to‐fuel energy conversion processes, charge carriers are the main and inevitable participators, and the charge dynamics related to their generation, migration, separation, and utilization is the key to advance the material design for settling the above issues. Internal electric field (IEF), also named as built‐in electric field, could guide directional migration of charge carriers, achieving effective charge separation, utilization, and prolonged lifetimes. This critical review begins with the discussion on various modulation strategies toward the IEF together with in‐detail elucidated mechanisms on its formation. Some cascade systems for telling the conclusive role from the induced IEF and the intrinsic design strategy are discussed. Then, a summary of the state‐of‐the‐art advances in the characterization means toward the IEF from both quantitative and qualitative perspectives is provided. Finally presented are IEF modulations in several specific energy‐related applications concerning solar cell, photocatalysis, photodetectors, and batteries to better understand its superiority for well‐performed material design, followed by perspectives on future development and opportunities of the IEF design.