Improved thin films of pentacene via pulsed laser deposition at elevated substrate temperatures

Abstract

Thin films of pentacene were deposited by thermal evaporation and by pulsed laser deposition (PLD). Surface characterization using atomic force microscopy shows that PLD leads to a reduction in surface roughness, which can be reduced further using heated substrates. Observation of enhanced field-effect carrier mobilities in the PLD films, together with increased electrical conductivity and reduced activation energy for electrical conduction, is consistent with increased molecular ordering in the pentacene films and suggests a direct correlation between molecular ordering in the bulk and surface roughness.

DNA detection using organic thin film transistors: Optimization of DNA immobilization and sensor sensitivity

“…As grain size increases, the mobility increases. Since electrical conductivity is limited by charge transfer across grain boundaries, the formation of larger crystallites leads to enhanced conductivity (Salih et al, 1996). Mobility increase leads to the current increase that we see in our experiment.…”

“…When evaporation of pentacene is done at higher substrate temperatures, the formation of the pentacene crystals on the surface is more ordered, thereby reducing the overall roughness. The effect of substrate temperature on the ordering of thin films of pentacene has been previously analyzed (Salih et al, 1996). The input current does not independently affect the mean roughness and is therefore not shown in Fig.…”

Mechanisms of Resonant Infrared Matrix-Assisted Pulsed Laser Evaporation

“…111 It is kinetically rather than thermodynamically controlled (in contrast to the spinodal). 110 The spinodal at a constant composition is specified by the criteria: 111 ∂P ∂V T = 0 and ∂T ∂S P = 0, [15,16] The previous equations are a consequence of the extremum principle of thermodynamics, which states that the entropy of a pure substance is at a maximum in a stable equilibrium state. 112 In its general form, the Redlich-Kwong equation reads: [17] where P is pressure, T is temperature, R is the gas constant, V m is the molar volume, and the numerical constants are determined from the following criticality conditions: [18,19] The previous equation of state approaches the ideal gas law as P decreases or T increases.…”

Inverted top-emitting organic light-emitting diodes using sputter-deposited anodes

“…Pentacene was chosen due to its superior hole-conducting properties 23 and its chemical stability towards exposure to intense UV light, elevated temperatures, 24 and water vapor. 25 A multilayer heterostructure containing three hole-transport layers ͑HTLs͒ was investigated in order to ensure balanced carriers statistics in the recombination zone.…”