STUDY OF THE PHOTOCONVERSION EFFICIENCY ON NANOSTRUCTURED SOLAR CELLS BASED ON TIO2 FILMS SENSITIZED WITH QDS AND DECORATED WITH AU NANOPARTICLES AND P3OT
ISAAC ZARAZUA MACIAS
ELDER DE LA ROSA (Thesis Adviser)
Summary or description
"Novel composite titanium dioxide (TiO2) films of 10 µm thickness have been prepared and characterized with emphasis on evaluating their photovoltaic properties. The films contain TiO2 nanocrystals (NCs) with anatase crystalline phase deposited on a substrate with a thin conductor oxide film, composited with CdSe quantum dots (QDs), Au nanoparticles (NPs), and poly(3-octylthiophene) (P3OT) in different configurations. In the case of single sensitized films, Au NPs considerably increases the FF of titania films, indicating that such NPs help to the charge carriers transport. P3OT slightly increases the photocurrent and FF of the TiO2 films, indicating that the polymer may acts as a photogenerator and as a hole conductor giving a relatively good cell performance. However, CdSe QDs sensitized films exhibited the largest photocurrent (237 µA/cm2) giving a photoconversion efficiency of 0.149%, overcoming the efficiency of the other two materials and giving a four-fold efficiency increase of not sensitized TiO2 (0.034%).
These results are attributed to the ability of QDs to photogenerate charge carriers efficiently giving a great amount of electrons to increase the photocurrent. With the introduction of Au NPs or P3OT into the TiO2/QDs films, the photocurrent increases up to ~85% and ~150% while the photoconversion efficiency increases by ~167% and ~177%, respectively. An interesting synergistic effect was observed when Au NPs and P3OT were used in conjunction. The configuration of TiO2/Au/QDs/P3OT film exhibits a photocurrent of 906 !A (an enhancement of ~285%) and the photoconversion efficiency of 0.661% (an enhancement of ~600%) compared to that of TiO2/QDs films. Such significant enhancement is attributed to the ability of Au NPs to facilitate charge separation and improve electron injection as well as P3OT’s ability to inject electrons and enhance hole transport avoiding electron recombination. Such ability when combined with the QD’s strong photoabsorption in the visible, lead to the overall increase in photocurrent generation, fill factor, and consequently photoconversion efficiency."
Zarazúa Macías, (2013). "Study of the photoconversion efficiency on nanostructured solar cells based on TiO2 films sensitized with QDs and decorated with Au nanoparticles and P3OT": Tesis de Doctorado en Ciencias (Óptica). Centro de Investigaciones en Óptica, A.C. León, Guanajuato. 106 pp.
REPOSITORIO INSTITUCIONAL DEL CIO