The effect of the Si-H bond on the gas-phase reaction chemistry of trimethylsilane in the hot-wire chemical vapor deposition (HWCVD) process has been studied by examining its decomposition on a hot tungsten filament and the secondary gas-phase reactions in a reactor using a soft laser ionization source coupled with mass spectrometry. Trimethylsilane decomposes on the hot filament via Si-H and Si-CH(3) bond cleavages. A short-chain mechanism is found to dominate in the secondary reactions in the reactor. It has been shown that the hydrogen abstractions of both Si-H and C-H occur simultaneously, with the abstraction of Si-H being favored. Tetramethylsilane and hexamethyldisilane are the two major products formed from the radical recombination reactions in the termination steps. Three methyl-substituted disilacyclobutane molecules, i.e., 1,3-dimethyl-1,3-disilacyclobutane, 1,1,3-trimethyl-1,3-disilacyclobutane, and 1,1,3,3-tetramethyl-1,3-disilacyclobutane are also produced in reactor from the cycloaddition reactions of methyl-substituted silene species. Compared to tetramethylsilane and hexamethyldisilane, a common feature with trimethylsilane is that the short-chain mechanism still dominates. However, a more active involvement of the reactive silene intermediates has been found with trimethylsilane.

Accelerated reliability tests of blue phosphorescent organic light-emitting diodes (OLEDs) comprising bis[(4,6-difluorophenyl)pyridinato-N,C2](picolinato)-iridium(III) (FIrpic) doped in four different wide bandgap hosts were conducted. The half-life of the OLEDs stressed under a high current density of 100 mA/cm2 varied in a wide range, revealing an important role of the host. Pulsed current stressing with a 1% duty cycle was performed to suppress self-heating, but only extended the lifetime by 2–3.2×. For blue OLEDs with a host favoring hole transport, current stressing caused a shift of the recombination zone toward the anode, turning the emission color to greenish blue. These results suggest that device degradation was mainly caused by charge-trapping defects generated within a narrow zone close to the electron-transport layer. It is expected that the lifetime of blue phosphorescent OLEDs can be effectively extended by selecting an appropriate host which has good stability, enables efficient charge injection and balanced charge transport in the emissive layer.