Carbon Nanotube Transparent Electrodes

Role of Dopants in Long-Range Charge Carrier Transport for p-Type and n-Type Graphene Transparent Conducting Thin Films

“…The two most important performance metrics for TCs are the transmittance ( T ) of incident photons and the sheet resistance, R s , which defines the resistance to two-dimensional charge carrier transport. Most solar cells utilize transparent conducting oxides (TCOs) that typically transmit at least 87% of the visible solar flux to the PV active layer and possess R s values in the 10–100 Ω/sq range . The majority of these TCOs, such as tin-doped indium oxide (ITO), fluorine-doped tin oxide (FTO), and cadmium-doped tin oxide (cadmium stannate), are n-type conductors with high carrier concentrations (>10 20 cm –3 ) arising from the introduction of atomic impurity dopants. , These high carrier concentrations limit the mobility via ionized impurity scattering and also lead to a large free carrier absorbance onset in the near-infrared, dramatically reducing the transmittance of photons with wavelengths greater than ∼1000 nm.…”