| AVS 61st International Symposium & Exhibition | |
| Electronic Materials and Processing | Friday Sessions |
| Session EM+NS+TF-FrM |
| Session: | Transparent Electronics |
| Presenter: | Jian-Zhang Chen, National Taiwan University, Taiwan, Republic of China |
| Authors: | Y.S. Li, National Taiwan University, Taiwan, Republic of China C.H. Tsai, National Taiwan University, Taiwan, Republic of China I.C. Cheng, National Taiwan University, Taiwan, Republic of China J.Z. Chen, National Taiwan University, Taiwan, Republic of China |
| Correspondent: | Click to Email |
Organic-inorganic hybrid materials can be deposited from hexamethyldisiloxane (HMDSO) diluted with oxidants using plasmas technology. The properties of the deposited material can be controlled by varying the dilution ratio of the oxidants. The chemical compositions can vary from polymer-like (organic-like) to SiO2-like (inorganic-like) depending on the oxidant dilution ratio and the process power. In this paper, we report two applications of HMDSO/O2-plasma-deposited organic-inorganic-hybrid materials developed in our group: (1) as gate dielectrics of MgZnO TFTs, and (2) as the encapsulation layers for organic-inorganic hybrid solar cells.
The inorganic/organic component ratios in hybrid films were tailored by varying the process power and the O2/HMDSO flow rate ratio. The FTIR analysis and contact angle measurement show that higher deposition power and/or larger O2/HMDSO flow rate ratio result in more SiO2-like films. For rf-sputtered MgZnO TFTs, a more organic-like film affords a better interface to the MgZnO active layer and higher dielectric constant, leading to a smaller threshold voltage and a steeper subthreshold slope; while an inorganic-like film has lower leakage currents, resulting in a larger on/off current ratio in the transistors. The TFT with an organic-inorganic-hybrid gate dielectric deposited at an O2/HMDSO ratio of 40 and process power of 30 W exhibits a threshold voltage of 6.8 V, a subthresold slope of 0.48 V/dec, an on/off current ratio of >107 and a linear mobility of ~60 cm2V-1s-1, respectively. We also have demonstrated that this O2/HMDSO-plasma-deposited organic-inorganic material can be used as an efficient single-layer encapsulation technique for organic photovoltaic cells. Calcium test was used to evaluate the water vapor transmission rate (WVTR) of the barrier film deposited on a polyimide foil. A water vapor transmission rate of 3.6×10-6 g/m2-day was obtained for a 1.5 um-thick single permeation layer. Inverted type organic photovoltaic passivated by the hybrid material was used to evaluate the effectiveness of this encapsulation. Efficiency decay was not observed in the cell coated with this encapsulation layer after 3000-hour exposure to the air; on the contrary, the un-encapsulated counterpart cell degraded rapidly and completely failed after 120-hour exposure to the air. The result shows that this single-layer hybrid material encapsulation can enhance the stability of organic photovoltaic cell. The cell life time is greatly improved.