A theoretical model for carrier transport in disordered organic materials

Device Optimization and Transient Electroluminescence Studies of Organic light Emitting Devices

“…41 These SCLC models (with or without traps) have been extensively used in studying the carrier transport processes in OLEDs and they are they are in good agreement with the experimental results. 25,45 When the I(V) curve exhibits a square-law dependence (/~ V 2 ), it is generally agreed that the conduction process is trap-free space-charge-limited.…”

“…41 Given ohmic contacts, the current-voltage relation of an organic semiconductor is linear at low fields but becomes nonohmic at higher values of that field. This behavior is, in general, due to two effects: (i) At the higher current densities corresponding to higher values of field, a relatively large concentration of charge carriers in transit to the collector electrode will be present between the electrodes.…”

“…Hence, the field-dependent mobility already implicitly presumes the presence of traps. 41 Thus, the traps and field-enhanced mobility effects should determine the I(V) curve together and it is hard to separate them.…”

Device optimization and transient electroluminescence studies of organic light emitting devices

“…T where 1 = 2 when the material is trap-free, and / = 1 + -(T C is a constant for the trap distribution, and T is the absolute temperature) when traps with an exponential energy distribution are present. 41 These SCLC models (with or without traps) have been extensively used in studying the carrier transport processes in OLEDs and they are they are in good agreement with the experimental results. 25,45 When the I(V) curve exhibits a square-law dependence (/~ V 2 ), it is generally agreed that the conduction process is trap-free space-charge-limited.…”

“…If the current through the device is dominated by the hopping mechanism between different sites, the current is called space charge limited current (SCLC). 41 Given ohmic contacts, the current-voltage relation of an organic semiconductor is linear at low fields but becomes nonohmic at higher values of that field. This behavior is, in general, due to two effects: (i) At the higher current densities corresponding to higher values of field, a relatively large concentration of charge carriers in transit to the collector electrode will be present between the electrodes.…”