Background:
The photo-absorption and light trapping through the different layers of the
organic solar cell structures are a growing concern now-a-days as it affects dramatically the overall
efficiency of the cells. In fact, selecting the right material combination is a key factor in increasing
the efficiency in the layers. In addition to good absorption properties, insertion of nanostructures has
been proved in recent researches to affect significantly the light trapping inside the organic solar cell.
All these factors are determined to expand the absorption spectrum and tailor it to a wider spectrum.
Objective:
The purpose of this investigation is to explore the consequence of the incorporation of the
Ag nanostructures, with different sizes and structures, on the photo absorption of the organic BHJ
thin films.
Methods:
Through a three-dimensional Maxwell solver software, Lumerical FDTD, a simulation and
comparison of the optical absorption of the three famous organic materials blends poly(3-
hexylthiophene): phenyl C71 butyric acid methyl ester (P3HT:PCBM), poly[N-9″-heptadecanyl-2,7-
carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)]: phenyl C71 butyric acid methyl ester
(PCDTBT:PCBM) and poly[2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b′]dithiophene)-alt-
4,7-(2,1,3-benzothiadiazole)]: phenyl C71 butyric acid methyl ester (PCDPDTBT:PCBM) has been
conducted. Furthermore, FDTD simulation study of the incorporation of nanoparticles structures with
different sizes, in different locations and concentrations through a bulk heterojunction organic solar
cell structure has also been performed.
Results:
It has been demonstrated that embedding nanostructures in different locations of the cell,
specifically in the active layer and the hole transporting layer had a considerable effect of widening the
absorption spectrum and increasing the short circuit current. The effect of incorporation the nanostructures
in the active layer has been proved to be greater than in the HTL. Furthermore, the comparison
results showed that, PCDTBT:PCBM is no more advantageous over P3HT:PCBM and
PCPDTBT:PCBM, and P3HT:PCBM took the lead and showed better performance in terms of
absorption spectrum and short circuit current value.
Conclusion:
This work revealed the significant effect of size, location and concentration of the Ag
nanostructures while incorporated in the organic solar cell. In fact, embedding nanostructures in the
solar cell widen the absorption spectrum and increases the short circuit current, this result has been
proven to be significant only when the nanostructures are inserted in the active layer following specific
dimensions and structures.
Carrier Formation Dynamics of Organic Photovoltaics as Investigated by Time-Resolved Spectroscopy
