Thank you for participating in the 81st Physical Electronics Conference 2021! https://sites.google.com/stonybrook.edu/pec2021 The Physical Electronics Conference provides a yearly forum for the dissemination and discussion of novel and fundamental theoretical and experimental research in the physics, chemistry, biology, and engineering of surfaces and interfaces. The conference draws from cutting edge research in material science; topics include structural, electronic, chemical, magnetic, or topological properties of surfaces and interfaces and thin films; electron correlation or processes of energy, electron, ion, and molecular transfer at surfaces and interfaces; energetics, kinetics, and dynamics of physical, chemical, and biological transformations; interactions of organic or biological materials; mechanisms of film growth, effects of reduced dimensionality, confinement or patterning. Presentations of Ph.D. thesis research, made by student contestants for the prestigious Nottingham prize ($1,500), are highlighted.