Transition metal oxide- upconverting nanoparticle systems for use in NIR detection (A personal achievement)

I have been working with transition metal oxides since 2005 (eg. WO3, TiO2). After starting my PhD at Ecole Polytechnique de Montreal in 2008, I started to work with Dr. Perepichkas group in McGill university who supplied upconverting nanoparticles for my project in hybrid organic-inorganic thin films for use in energy harvesting in the lost region of the solar spectrum. Here, the lost region implies the NIR region. Usually solar cells do not absorb in this area.  I worked with Hexagonal NaYF4: Yb, Er nanoparticles for that study.

Keeping in mind that the energy transfer between species in close proximity and with a good energy level alignement can take place, I wanted to see how ucNP will behave when dispersed in a transition metal oxide matrix. Close to the end of my PhD, I designed an experiment using the nanoparticles provided by Dr. Perepichkas laboratory and the WO3 which I synthesized in the laboratory by sol-gel method. I mixed the  ucNP with the prepared solution of WO3 and deposited a thick layer of the mixture onto a substrate with an ITO electrode (1000 um channel). The device was prepared as a 2 electrode device.    

Finally, I connected the electrodes to an Agilent B2100 series semiconductor parameter analyser unit and applied a potential between the two electrodes under dark conditions. The sample was kept under a black curtain during the experiments. When there was no excitation at the channel I did not observe any current flow in the channel. However, wehenever I excited the channel with a NIR (980 nm) laser I started to observe a current increase. I started to excite the ucNP-WO3 channel with NIR laser with intervals ( on-off) and I observed that the current was behaving accordingly. As a second step I increased the applied potential and observed an increase in the current flow as well. While increasing the current, I kept the laser power same. So, the only variable was the applied potential.

To my knowledge, this made me the first person to show this kind of a current generation in a transition metal oxide- upconverting nanoparticle system.

I would like to work more on this project later when I have my own laboratory.

This work of mine lead to a collaboration with Ludvig Martinu group at Ecole Polytechnique de Montreal for NSERC grant application and collaborative work with Fiorenzo Vetrone group at INRS. The work was presented in several conferences. In the latest conferences my name was not included in the work. Probably because I am not a part of the group anymore, however the idea and the first demosntration of the principle belongs to me.

If you are interested in knowing more, or if you are interested in the details of the work I will be glad to share my expertise in this area.