chapter 1. Introduction to energy devices -- chapter 2. Electrostatic and thermodynamic potentials of electrons in materials -- chapter 3. Voltage, capacitors, and batteries -- chapter 4. Work functions and injection barriers -- chapter 5. Thermal distribution of electrons, holes, and ions in solids -- chapter 6. Interfacial kinetics and hopping transitions -- chapter 7. The chemical capacitance -- chapter 8. The density of states in disordered inorganic and organic conductors -- chapter 9. Planar and nanostructured semiconductor junctions.