Current-voltage behavior in hole-only single-carrier devices with self-assembling dipole molecules on indium tin oxide anodes

Abstract

The authors report the use of chemically modified indium tin oxide (ITO) with different binding groups (–COCl and –PO2Cl2) of p-chlorobenzene derivatives forming effective monolayers to control the work function of ITO and hence to enhance the hole injection. The enhanced hole injection is studied by measuring current density–voltage (J-V) characteristics. The behavior of J-V characteristics caused by varying the ITO work function in hole-only single-carrier devices with a hole transport layer of N,N′-diphenyl-N,N′-bis(3-methylphenyl)-1,1′-biphenyl-4,4′-diamine is examined. Upon grafting with p-chlorophenylphosphoryl dichloride, the J-V characteristics show a space-charge-limited conduction behavior. Such modified ITO anodes lead to improvements in the device properties.

Insertion of an organic interlayer for hole current enhancement in inverted organic light emitting devices

“…And typical space charge limited current is observed above the voltages of 8 V ͑without HAT-CN͒ and 1 V ͑with HAT-CN͒, respectively. 18,19 This result corroborates the fact that the insertion of HAT-CN ͑20 nm͒ as HIL significantly improves the device property.…”

Spatially Modulating Interfacial Properties of Transparent Conductive Oxides: Patterning Work Function with Phosphonic Acid Self‐Assembled Monolayers

“…Second, while silanes can be microcontact printed onto oxides, they can often exhibit spreading and poor fidelity unless they are microcontact printed onto hot substrates. [18,19] Fujihira and co-workers shifted the ITO work function using benzoyl-and phosphoryl-chlorides, [28,29] and microcontact printed these molecules to give patterned electroluminescence. [27] However, the resulting contact potential difference (CPD) contrast between patterned and unpatterned SAM regions of the ITO substrate was significantly lower than the CPD shift measured on ITO that had been soaked in a SAM solution, suggesting poorer ordering or lower density of the microcontact printed SAMs relative to solution-deposited SAMs.…”

Improvement of Open-Circuit Voltage in Organic Photovoltaic Cells with Chemically Modified Indium-Tin Oxide

“…Figure 2(a) shows the room temperature J-V bias characteristics of ITO(variously treated)/C 60 (60 nm)/Al single-layer cells with a focus on the dark conduction properties. A linear fitting of the log-log plot (not shown) for these cells shows that the current for forward bias (electrons injection from the top contact) increases much slower (a slope is ~1) than the space-charge limited conduction (SCLC) [36]. Conducting charge transfer complex formed on C 60 /metal interface was studied in previous report [37].…”