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A D V A N C E D M A T E R I A L S & P R O C E S S E S | N O V E M B E R / D E C E M B E R 2 0 1 5

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University of California, Los Ange-

les Professor Yang Yang and his team re-

port they have conquered the primary

obstacle of perovskite by protecting it

between two layers of metal oxide—a

significant advance toward stabilizing

perovskite solar cells. Their new cell

construction extends the cell’s effective

life in air by more than 10 times, with

only a marginal loss of efficiency in con-

verting sunlight to electricity.

Yang says there are several fac-

tors that lead to quick deterioration in

normally layered perovskite solar cells.

The most significant is that the widely

used top organic buffer layer has poor

stability and cannot effectively protect

the perovskite layer from moisture in

the air, speeding cell degradation. The

buffer layers are important to cell con-

struction because electricity generated

by the cell is extracted through them.

The team replaced those organ-

ic layers with metal oxide layers that

sandwich the perovskite layer, protect-

ing it from moisture. The difference is

dramatic. The metal oxide cells lasted

60 days in open-air storage at room

temperature, retaining 90% of their

original solar conversion efficiency.

The next step is to make the metal

oxide layers more condensed for better

efficiency and to seal the solar cell for

even longer life with no loss of efficien-

cy. Yang expects that this process can

be scaled up to production now that

the main perovskite problem has been


For more information: Yang

Yang, 310.825.4052,






Helmholtz-Zentrum Berlin, Germa-

ny, researchers are inquiring how to use

Perovskite solar cells with metal oxide hole and electron transport layers.

Courtesy of Tunde Akinloye/CNSI.


Researchers from the

University of Kashan,

Iran, produced nanostructures

in bar form and studied their performance in dye-sensitized solar cells. Core-

shell structures made of zinc oxide and titanium oxide were grown on indium

tin oxide beds in nanobar form. Results show that the nanostructures have

high transparency in the visible light range and have lower electrical resistance

compared to common samples. The high transparency enables adsorption of

larger wavelengths in the visible light range—an important step in increasing



nanoparticle arrangements to improve

solar cells and other opto-electronic de-

vices. CIGSe solar cells have proven high

efficiencies and are established thin

film devices with active layers of a few

micrometers thickness. But, because in-

dium is a rare element, the active layer

should be as thin as possible, reducing

efficiency, as less light is absorbed. “It

took me more than a year to be able

to produce ultrathin layers of only



m or 460 nm, which still reach rea-

sonable efficiencies up to 11.1%,” says

Ph.D. student Guanchao Yin.

Colleagues in Amsterdam pro-

duced an array of SiO



directly on the molybdenum substrate,

which corresponds to the back contact

of the solar cell. On top of this struc-

tured substrate, Yin grew an ultrathin

CIGSe layer, followed by all other layers

and contacts needed for the solar cell.

With this configuration, efficiency in-

creased from 11.1% to 12.3%, and the

short circuit current density of the ultra-

thin CIGSe cells increased by more than

2 mA/cm


. With additional antireflective

nanoparticles at the front, efficiencies

grew to 13.1%.

Further studies indicate that the

nanoarray of dielectric SiO



cles at the back side could also increase

efficiencyby reducing chances for charge

carrier recombination.

For more infor-

mation: Guanchao Yin, 030.8062.43721,