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Free keywords:
Theoretical or Mathematical, Experimental/ electron-hole recombination; elemental semiconductors; excitons;
germanium; nanoparticles; silicon; solar cells/ solar energy conversion; 3G photovoltaic cells; Schockley-Quessier
limit; solar cell energy conversion; multiple exciton generation;
electron-hole pair emission; quantum confinement; solar spectrum; exotic
high-pressure phase; absorption; cubic diamond phase; MEG rates;
colloidal NP; laser treated surface; exotic nanoparticle systems; solar
applications; Si; Ge/ A8630J Photoelectric conversion; solar cells and arrays
B8420 Solar cells and arrays/ Si/el; Ge/el;
Abstract:
Third generation photovoltaic cells promise to overcome the
Schockley-Quessier limit of solar cell energy conversion. In the
Multiple Exciton Generation (MEG) pathway quantum confined highly
energetic electron-hole pairs relax by emitting additional electron-hole
pairs. The overall utility of this process is undermined, however, by
the very fact that quantum confinement pushes the gap of nanoparticles
(NPs) out of the solar spectrum. Here we propose that Si and Ge NPs with
core structures made out of exotic high-pressure phases of bulk Si and
Ge have lower gaps, more intense absorption and higher MEG rates than
those of made out of the cubic diamond phase. Some of these exotic
phases have already been proven to exist in colloidal NPs or on laser
treated surfaces, therefore, our findings may open the door for
promising solar applications of such exotic nanoparticle systems.
