The SCLC method can be described via the Mott-Gurney equation (3), and the carrier mobility (μ) of organic semiconductors can be calculated according to the Poole-Frenkel equation ( ), where the ε0 is the free-space permittivity (8.85 × 10 -14 C V -1 cm -1 ), εr is the relative dielectric constant (assumed to be 3.0 for organic semiconductors), E is the electric field, μ0 is the zero-field mobility, and γ is the Poole-Frenkel factor and L is the thickness of the neat film of each molecule.