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Li T.,Nankai University | Li T.,Key Laboratory of Photo electronic Thin Film Devices and Technology of Tianjin | Zhang X.,Nankai University | Zhang X.,Key Laboratory of Photo electronic Thin Film Devices and Technology of Tianjin | And 16 more authors.
Solar Energy | Year: 2016

Carbon dioxide plasma (COP) treatment of a fluorine-doped tin oxide (SnO2:F, FTO) front electrode was used for the fabrication of p-i-n hydrogenated amorphous silicon (a-Si:H) solar cells. The oxygen and carbon monoxide radicals in COP play important roles of de-doping and doping effects on the surface of FTO, respectively. Through changing the COP treatment time, the de-doping and doping effects could alter the number of oxygen vacancies for both the bulk and the surface of FTO, resulting in an increase in the work function (WF) and a decrease in the Schottky barrier at the p-a-SiC:H/FTO interface. Due to an increase in the WF from 4.16 eV to 4.34 eV after 95 s treatment, the open circuit voltage (Voc) of the a-Si:H solar cells increased from 915 mV to 965 mV and the fill factor (FF) increased from 67.7% to 74.4%. Although the short-circuit current density (Jsc) decreased from 11.76 mA/cm2 to 10.36 mA/cm2 after 95 s COP treatment due to the weakness of Burstein-Moss (BM) shift and the recombination at FTO surface, the conversion efficiency of the a-Si:H solar cell was enhanced by 12.24% after 45 s COP treatment, accompanied by improving the Voc and FF with almost constant Jsc. © 2016 Elsevier Ltd.


Li T.-T.,Nankai University | Li T.-T.,Key Laboratory of Photo electronic Thin Film Devices and Technology of Tianjin | Yang T.,Nankai University | Yang T.,Hebei University of Technology | And 16 more authors.
Chinese Physics B | Year: 2016

Phosphorous-doped hydrogenated nanocrystalline silicon oxide (n-nc-SiOx:H) films are prepared via radio frequency plasma enhanced chemical vapor deposition (RF-PECVD). Increasing deposition power during n-nc-SiOx:H film growth process can enhance the formation of nanocrystalline and obtain a uniform microstructure of n-nc-SiOx:H film. In addition, in 20s interval before increasing the deposition power, high density small grains are formed in amorphous SiOx matrix with higher crystalline volume fraction (I c) and have a lower lateral conductivity. This uniform microstructure indicates that the higher I c can leads to better vertical conductivity, lower refractive index, wider optical band-gap. It improves the back reflection in a-Si:H/a-SiGe:H tandem solar cells acting as an n-nc-SiOx:H back reflector prepared by the gradient power during deposition. Compared with the sample with SiOx back reflector, with a constant power used in deposition process, the sample with gradient power SiOx back reflector can enhance the total short-circuit current density (J sc) and the initial efficiency of a-Si:H/a-SiGe:H tandem solar cells by 8.3% and 15.5%, respectively. © 2016 Chinese Physical Society and IOP Publishing Ltd.


Xie X.J.,Hebei University of Technology | Wang W.H.,Nankai University | Wang W.H.,Key Laboratory of Photo Electronic Thin Film Devices and Technology of Tianjin | Li L.Y.,Shandong Jianzhu University | And 4 more authors.
Applied Mechanics and Materials | Year: 2013

We investigate the electronic structures and optical properties of ZnO with antisite defects OZn using the density function pseudopotential method. Our results show that the Fermi level shifts into the conduction band after introducing one or two OZn defects into ZnO supercell, indicating that the system displays a metallic-like characteristic. Moreover, the antisite defects lead to a redshift of the optical absorption edge and obvious optical absorption in the visible light region. Especially, the optical properties are influenced by the configurations of two OZn defects in our considered ZnO supercell. The strongest optical absorption occurs when the two defects are connected by -Zn-O-Znbond in the ab plane. These findings are possibly applicable for designing new optoelectronic and photoelectrochemical devices with improved low energy light absorption. © (2013) Trans Tech Publications, Switzerland.

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