Chenning Wang,Xiaoyu Zhou,Tianqi Jiang,Zhenrui Xu,Esmond A. Balfour,Hao Fu
The high content of Ba and Sc in Ba
$_{\text{3}}$
ScGa
$_{\text{2}}$
O
$_{\text{7.5}}$
and its suitable melting point suggest that it is a candidate for thermionic emission in vacuum electron devices. To study its electron emission capacity, this compound was synthesized at 1300
$^{\circ}$
C by a high-temperature solid-phase method with the stoichiometric mole ratio of BaCO
$_{\text{3}}$
:Sc
$_{\text{2}}$
O
$_{\text{3}}$
:Ga
$_{\text{2}}$
O
$_{\text{3}}$$=$
6:1:2. The test cathode impregnated with this material had a high emission capacity with the full-space charge current density of 10.2 A/cm
$^{\text{2}}$
at 850
$^{\circ}$
C in the dc mode. The sintered mixture of the compound and tungsten powder reveals that the formation of Ba
$_{\text{3}}$
Sc
$_{\text{2}}$
WO
$_{\text{9}}$
on the cathode surface leads to reduced work function and thus enhanced emission performance. The titled compound is environmentally stable with a low weight gain percentage (4.51%) and a steady phase in the air for 288 h. Coupled with the high emission current density at low temperatures, the cathode impregnated with Ba
$_{\text{3}}$
ScGa
$_{\text{2}}$
O
$_{\text{7.5}}$
compound has superior thermionic cathode properties and promising applications in vacuum electron devices.
We report on a low work-function (WF), high-conductivity poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) electrode by a two-step dipping process. The first dipping into the sulfuric acid is to enhance its conductivity and the second dipping into PEI solution is to lower its work function. After the first dipping, the conductivity of PEDOT:PSS film reaches 1561 S/cm under dipping time of 1 min and the temperature of 60 °C. After dipping into sulfuric acid, the thickness of PEDOT:PSS is reduced to about half but the transmittance was lowered. After the dipping into the PEI solution, the WF of PEDOT:PSS is reduced from 4.9 to 4.0 eV. Although the conductivity were lowered slightly after treated with PEI solution, an electrode with a high conductivity of 1140 S/cm was achieved. The low WF and high-conductivity PEDOT:PSS film is used to fabricate ITO-free, metal-electrode-free and vacuum-free organic solar cells with a simple structure of glass/low-WF PEDOT:PSS/P3HT:ICBA/high WF-PEDOT:PSS, the cells display a fill factor of 61% and a power conversion efficiency of 4.0% under 100 mW/cm 2 white light illumination.
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