UJI activities atITN-DESTINY

Dr. Eva M. BareaLuca BertoluzziDr. Francisco Fabregat-SantiagoProf. Juan Bisquert

3G Solar identified that ageing of dye solar cells produced in most of cases a photocurrent decay associated with a small increase in Voc

Effects of ageing on DSC modules

Changes in the coloration of the cells were not observed, despite temperature rose to 62ºC (from 26 ºC ambient) in operating cells

Impedance analysis allowed to identify that electrical contributions to this behaviour were governed by upwards shifts in conduction band which produces a decrease in recombination and thus the observed increase in photo-potential.

Effects of ageing on DSC modules

When Recombination and capacitance data are displaced the shift in the conduction band, no changes are observed between the two samples .

Effects of ageing on DSC modules

A part of small changes in charge transfer at counter electrode and FTO resistance, no significant differences were observed in the other electrical contributions of operating and degraded cells

Effects of ageing on DSC modules

Vapp (V)

0.0 0.2 0.4 0.6 0.8

j (m

A·c

m-2

)

0

2

4

6

8

10

12

141 % 0.1 %

Water (1% and 0.1%) was added to the electrolyte to explore if origin of these deviations was originated by absorbed humidity after long term aging.

Effects of ageing on DSC modules

While the sample with low contetns of water degraded after 10 days, the sample with 1% water kept stability.

Again the electrical differences found between these two samples could be ascribed to changes in Ec.

Effects of ageing on DSC modules

VF (V)

0.3 0.4 0.5 0.6 0.7 0.8

Cap

acita

nce

(F·c

m-2

)

10-5

10-4

10-3

10-2

1%0.1%

VF (V)

0.3 0.4 0.5 0.6 0.7 0.8

Res

itanc

e (

·cm

2)

1

10

100

1000

10000

Again the electrical differences found between these two samples could be ascribed to changes in Ec.

Effects of ageing on DSC modules

Vecb (V)

0.2 0.3 0.4 0.5 0.6 0.7 0.8

Cap

acita

nce

(F·c

m-2

)

10-5

10-4

10-3

10-2

1%0.1%

Vecb (V)

0.2 0.3 0.4 0.5 0.6 0.7 0.8

Res

itanc

e (

·cm

2)

1

10

100

1000

10000

Conclusions:

Degradation of cell performance is (mainly) due to a rise of conduction band that limits light injection from the dye at a larger extent than the corresponding Voc rise.

The behavior observed may not be related with water contents. Actually, It seems that certain contents of water protects the cell performance in long term measurements.

Effects of ageing on DSC modules

On the methods of calculation of the charge collection efficiency of dye sensitized solar cells, Luca Bertoluzzi and Shuai Ma Phys. Chem. Chem. Phys. (2013) 15, 4283-4285

Theory of Impedance Spectroscopy of Ambipolar Solar Cells with Trap Mediated Recombination, Luca Bertoluzzi, Pablo P. Boix, Iván Mora-Seró, Juan BisquertJournal of Physical Chemistry C, just accepted manuscript, (2014)

Relaxation of electron carriers in the density of states of nanocrystalline TiO2

Luca Bertoluzzi, Isaac Herraiz-Cardona, Ronen Gottesman, Arie Zaban, Juan Bisquert. Sent for publication to Journal of Physical Chemistry Letters (2014)

Published papers