Abstract
Controlling defect states in a buffer layer for organic photo devices is one of the vital factors which have great influence on the device performance. Defect states in silicon oxynitride (SiOxNy) buffer layer for organic photo devices can be controlled by introducing appropriate dopant materials. We performed ab initio simulations to identify the effect on doping SiOxNy with carbon (C), boron (B), and phosphorous (P) atoms. The results unveil that hole defects in the SiOxNy layer diminish with the phosphorous doping. Based on the simulation results, we fabricate the small molecule organic photodetector (OPD) including the phosphorous-doped SiOxNy buffer layer and the active film of blended naphthalene-based donor and C60 acceptor molecules, which shows excellent enhancement in the external quantum efficiency (EQE). The results of our charge-based deep level transient spectroscopy (Q-DLTS) measurements confirmed that the EQE enhancement originates from the decrease of the hole traps induced by the reduced hole defects. The method of controlling the defect states in SiOxNy buffer layers by the doping can be used to improve the performance in various organic photo devices.
Highlights
Controlling defect states in a buffer layer for organic photo devices is one of the vital factors which have great influence on the device performance
There has been a plenty of effort to improve the device performances of organic photodetector (OPD) including external quantum efficiency (EQE), dark current (DC), and thermal stability, which are the key factors to evaluate the performance of OPDs4–13
The Si-rich SiOxNy films were sequentially deposited on indium tin oxide (ITO)-coated glasses by plasma-enhanced chemical vapor deposition (PECVD) using various SiH4:NH3:N:PH3 gas mixtures with carrier N2 gas; 670 W of RF power was applied and the deposition temperature was 180 °C
Summary
Controlling defect states in a buffer layer for organic photo devices is one of the vital factors which have great influence on the device performance. The method of controlling the defect states in SiOxNy buffer layers by the doping can be used to improve the performance in various organic photo devices. Because organic materials in OPDs are exposed to high temperature process such as post-annealing, passivation step, top layer planarization, and microlens forming process, they should be thermally stable without performance degradation Appropriate buffer layers such as MoOx, WOx, VOx, and triphenylamine derivative (TPD) has been introduced in the OPD fabrication for decreasing DC and enhancing thermal stability[14,15,16,17,18]. P achieve excellent enhancement in EQE of our OPD device including the SiOxNy buffer layer which had reduced defect states by doping with P atoms
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