Charge-carrier mobility in organic molecular

Charge-Carrier Mobilities in Organic Molecular Crystals 263... 

Theoretical Framework for Charge Carrier Mobility in Organic Molecular Solids... 

The mobihties /t of the charge carriers in the materials from which OLEDs are fabricated are low in comparison to the mobilities in organic molecular crystals (see Chap. 8). Furthermore, they are very different in the different materials there are some materials in which predominantly electrons are transported (fig ft),), and some in which mainiy holes participate in the transport (/t), /tg). Hole-transport materials, e.g. the naphthyl-phenyldiamine-biphenyl derivative NPB, have a relatively low ionisahon energy and therefore form radical cations preferentially and reversibly. Electron transport materials, e.g. Alqs, have a relatively high electron affinity and thus form radical anions preferentially and reversibly. 

Charge-carrier mobilities in amorphous disordered organic photo-conductive polymers that include molecularly doped polymers are typically near or below 10" m V s at E 10 Vm and T 295K. a-Conjugated silicon backbone polymers under similar conditions display hole mobilities around 1 m V s [40, 41]. 

---