title: High charge-carrier mobility enables exploitation of carrier multiplication in quantum-dot films.
abstract: Carrier multiplication, the generation of multiple electron-hole pairs by a single photon, is of great interest for solar cells as it may enhance their photocurrent. This process has been shown to occur efficiently in colloidal quantum dots, however, harvesting of the generated multiple charges has proved difficult. Here we show that by tuning the charge-carrier mobility in quantum-dot films, carrier multiplication can be optimized and may show an efficiency as high as in colloidal dispersion. Our results are explained quantitatively by the competition between dissociation of multiple electron-hole pairs and Auger recombination. Above a mobility of ~1 cm(2) V(-1) s(-1), all charges escape Auger recombination and are quantitatively converted to free charges, offering the prospect of cheap quantum-dot solar cells with efficiencies in excess of the Shockley-Queisser limit. In addition, we show that the threshold energy for carrier multiplication is reduced to twice the band gap of the quantum dots.
authors: Optoelectronic Materials section, Department of Chemical Engineering, Delft University of Technology, Julianalaan 136, 2628BL Delft, The Netherlands.
authors: C S Suchand
authors: CS
authors: Sandeep
authors: Sybren
authors: S
authors: ten Cate
authors: Juleon M
authors: JM
authors: Schins
authors: Tom J
authors: TJ
authors: Savenije
authors: Yao
authors: Y
authors: Liu
authors: Matt
authors: M
authors: Law
authors: Sachin
authors: S
authors: Kinge
authors: Arjan J
authors: AJ
authors: Houtepen
authors: Laurens D A
authors: LD
authors: Siebbeles
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