nanocomponents based on nanocrystals called nanocrystalline photovoltaic devices. Unlike traditional solar cells, these new type of cells mimic the principles of solar-energy conversion that natural photosynthesis has successfully adopted over the last 3.5 billion years. They perform the two functions of harvesting light and transporting charge-carriers in two separate steps. A prototype of such nanocrystalline devices, invented at the Ecole Polytechnique de Lausanne, is based on a process called dye sensitisation. Prof Graetzel explained the principle: this new type of solar cell involves what is called sensitiser molecules, and a nanocrystalline film of titanium dioxide (TiO2). The sensitiser molecules anchored onto the surface of the TiO2 film absorb the light and inject an electron into the oxide particles, which is transported to convert the light into electricity. Dye sensitised solar cells have been around for 30 years. TiO2 sensitisation was tested in 1985 and the process went to mass production in 2009 in the form of power windows – electricity producing windows. Compared to the traditional silicon based solar cells, this technology is much cheaper and more efficient. “Dye sensitised solar cells achieve power conversion efficiency over 10 percent,” Prof Graetzel enthused. They are also able to harvest and convert a larger proportion of the light spectrum– everything less than 900nm – which means that they have a broader absorption in infrared compared to traditional solar cells. They can also harvest at low light, interesting for indoor settings, or in countries such as Ireland. Edward Crossland, postdoctoral researcher at Oxford, is also working on a project involving sensitised solar cells. He believes the potential applications are numerous. “This nanocomponent would be the way to go for power roof or power windows with many colours, instead of the boring grey and opaque traditional power panels.” Changing colour window panes or flower lamps can also become elegant ways to join utility and aesthetics. But the potential applications are not limited to aesthetics. “Sunglasses made of hybrid cells could replace batteries and charge iPods,” Dr Crossland said. “We can also make solar powered bags that produce light during the night.” Dr Graetzel was particularly impressed by the use of dye-sensitised solar cells as cheap sources of light in the power cuts caused by the 2004 Tsunami. “It is a great satisfaction for science to contribute to solving problems at such critical times,” he said.
The XXI century wonder material
There has been the Bronze Age, the Iron Age, the Steel age, and the Silicon age. The XXI century will be the age of graphene. This is according to Lazlo Péter Biro, researcher at the Research Institute for Technical Physics and Materials Sciences, Hungary. He calls graphene “the wonder material of the XXI century.” Graphene is made of carbon-like graphite or diamond, but it’s two rather than three-dimensional. Thanks to its one atom thick planar structure - the thinnest possible material you can imagine — it combines a unique set of electrical and mechanical properties: “a combination that we thought for a long time was not possible in one single element,” said Prof Biro. As well as being the strongest material ever measured, graphene is also an excellent electric conductor. What’s more, it is easily stretched. Prof Biro explained that graphene’s amazi ?r&?W'F?W2&R?FR?76?&?RF???2F?F?ffW&V?B6?&7FW&?7F?72&W6V?B??Gv?F?ffW&V?B7'?7F???w&??2F?&V7F???2?v?B?R6??VB???&?&&??2v?F?Gv??&?V?FF???2??( ?B?2?W?G&?&F??'?V?V7G&???27G'V7GW&^( ??&?b&?&?6??6?VFVB???v??FW"F?BF?RGv?&W6V&6?W'2v??F?66?fW&VB?B??#B?&?F?g&??F?RV??fW'6?G??b??6?W7FW"?vW&Rv&FVBF?R??&V?&??R?7B?V"f?"F?V?"6??G&?'WF???F???w&?V?R&W6V&6??&W6V&6?gV?FVB'?F?RWW&?V?&W6V&6?6?V?6???( ??G&RvV???B???7F?F????f?6V??bW6VB&??6??b6&&???B6??R66?F6?FRF?7&VFRw&?V?R??Wr?FW&??v?F?W?G&?&F??'?&?W'F?W2?( ??6??WfV?V?BF?Bv2????r?&?F?f?"?G2F??B??W'6V?b6???6?G??BF?R&W7V?G2?66?&F??rF?&?b&?&??F?R?FV?F??f?"?6F???2?2V?F?W72???F?R?V"gWGW&R?6?V?G&?7&V?B?w&?V?RV?V7G&?FW2v???&RW6VB????F?f??F?26V??2?BF?V6?67&VV?2?F???2F?w&?V?^( ?27G&WF6?&?R&?W'F?W2???W"???R67&VV?6?V?B&RW?FV?FVBF?&R&VB2?Ww7W"??"?G26?R6?V?B6??vRF?GW&??B??F?'&6V?WB?&?b&?&?&V?WfW2?B?2?GFW"?b???fWr???F?2F???R?V"&Vf?&R6?WF???&V7F'G2F?&?GV6R6?7V?r???W2v?F?7G&WF6?&?RF?V6?67&VV???B6???"???W2&R7W'&V?F?&V??rFWfV??VB'???????7B'WB??B?V7B???F?R???vW"'V?w&?V?R?v?B?????"&??R??V?V7G&???72?BF?R???V?B?v?B?2???FW&??r?G2FWfV???V?B?????V?V7G&???72?2F?Bw&?V?RG&?6?7F?'26???B&R7v?F6?VB?fb( 2F??2?2???"?'7F6?RF???F?v?F??6F??????FVVB?v?&???r27v?F6??2?W76V?F??gV?7F????b6??6??G&?6?7F?'2??'WB6??WF???2&R&V??rf?V?Bv??6???f??fR&R?V?v??VW&??r?G27G'V7GW&R?F?R?FV?2F???F?g??G27W&f6R??6??'?6??G&????rF?RWF6???r&?6W72?BF?R7'?7F???w&??26??F?F???2?&?b&?&??2?6?F?fS?( ?w&?V?Rv???WfV?GV??&W?6R6??6???( ??????TD?4??P?????'F?6?W2f?"F?W&??BF?v??6?2?b??V??W.( ?2F?6V6P???d??rv?g&????6?72?B???7'?7F???R7G'V7GW&W2?F?Rf????v??r7V?W'2&W6V?FVB?fR66?V?6R&??V7G2????r&??6??rW6R?bV?v??VW&VB&?????V7V?W2????&V???rF?F?Rf7B&V??b????VF?6??R???R7V6?&??V7BF6??VB??V??W.( ?2F?6V6RW6??rvV?????v????'F?6?W26??VB??6??W2???6??W2??R'F?7V?&?vV???7V?FVBF???2f?"????VF?6??R??FR?b??B&???W'2?F?W6R'F?f?6???&W&VBfW6?6?W2&R&??6??F?&?R?????F???2?&??FVw&F&?R??BV7?F?&W&R???7B???'F?F??F?V?"7W&f6R6?&RV?v??VW&VBF?W&f?&??V?F??RgV?7F???2??76????76W&????g&??F?RV??fW'6?G??????&?6?66??F???2W6??r7V6????'F?6?W2F?F&vWB????B?VW2?vV?????v?fVGW&R?b??V??W.( ?2?F?W6R6??6?7B??F?R67V?V?F????b??6??V&?R&?FV??vw&VvFW26??VB????B?&WF?&?b?76W&???vV?B??F?FW67&?&RF?RF?&VRgV?7F???2??6??W2?fRF?&Rv?fV?F?&RGW&?VB??F?vV??v??7B??V??W.( ?2?f?'7F?F?W??fRF?72F?R&???B'&??&'&?W#?F?V?F?W??fRF?&R&?RF?&??BF?????F&WF?BF??&F?&W6V&6?W'2?fRF?&R&?RF???v??v?BF?V?'???v??rFV6???VW2?44?T?4R5???77VRC?vR#p???