Perhaps the most distinct feature is the nature of light absorption. In silicon, light creates free electrons and holes. In organic semiconductors, the low dielectric constant (ε ≈ 3-4) means that Coulombic attraction between an electron and a hole is strong. Thus, photoexcitation creates a bound electron-hole pair known as a , with a binding energy of 0.1–1.0 eV.
Due to structural disorder, electronic states are often localized on individual molecules or polymer segments rather than being delocalized across the entire crystal. 2. Charge Transport: The Polaron Model
Understanding these requires a solid grasp of Poisson’s equation, continuity equations, and drift-diffusion models adapted for disordered media. physics of organic semiconductors pdf
If you are studying the , it helps to think of them not as rigid metal wires, but as a busy crowd of people trying to pass messages across a room.
: When an electron moves, it's so heavy and the material so soft that the electron actually deforms the lattice around it, like a heavy ball rolling on a mattress. This "distorted package" is called a polaron . 3. Excitons: The Buddy System Perhaps the most distinct feature is the nature
Traditional fluorescent emitters only harvest singlets, but modern physics-based approaches like and phosphorescence allow for 100% internal quantum efficiency by harvesting triplets. 5. Applications and Future Directions
: Their electrons jump across a gap (π-π* transitions) typically between 1.5 and 3 eV, which is perfect for interacting with visible light . 🏃 The "Story" of the Electron: How they move when a photon is absorbed
A major section in any organic semiconductor PDF is the physics of excitons. In silicon, when a photon is absorbed, it creates a free electron and a free hole. In organic semiconductors, absorption creates a bound electron-hole pair known as an exciton.