Archive – 2014

Improved electronic coupling in hybrid organic-inorganic nanocomposites employing thiol-functionalized P3HT and non-toxic bismuth sulfide nanocrystals

We report in a recent article in Nanoscale how we employ a thiol-functionalized polymer (P3HT-SH) as a leverage to tailor the nanomorphology and electronic coupling in polymer-nanocrystal composites for hybrid solar cells. The presence of the thiol functional group allows for a highly crystalline semiconducting polymer film at low thiol contents and allows for improved nanomorphologies in hybrid organic-inorganic systems when employing non-toxic bismuth sulfide nanocrystals. Exciton dissociation efficiency and carrier dynamics at this hybrid heterojunction are investigated through photoluminescence quenching and transient absorption spectroscopy measurements, revealing a larger degree of polaron formation when P3HT-SH is employed, suggesting an increased electronic interaction between the metal chalcogenide nanocrystals and the thiol-functionalized P3HT. The fabricated photovoltaic devices show 15 % higher power conversion efficiencies as a result of the improved nanomorphology and better charge transfer mechanism together with the higher opencircuit voltages arisen from the deeper energy levels of P3HT-SH.

Reference: Luis Martinez, Sosuke Higuchi, Andrew Maclachlan, Alexandros Stavrinadis, Nichole Cates Miller, Silke Luzia Diedenhofen, Maria Bernechea, Sean Sweetnam, Jenny Nelson, Saif Ahmed Haque, Keisuke Tajima and Gerasimos Konstantatos
Improved electronic coupling in hybrid organic-inorganic nanocomposites employing thiol-functionalized P3HT and non-toxic bismuth sulfide nanocrystals
Nanoscale 6, 10018-10026 (2014)

Determination of carrier lifetime and mobility in colloidal quantum dot films via impedance spectroscopy

We report in a recent article in Applied Physics Letter that we employ impedance spectroscopy to determine the carrier lifetime in PbS quantum dot Schottky solar cells and we verify the validity of the technique via transient photovoltage. We also present a simple approach based on an RC model that allows the determination of carrier mobility in PbS quantum dot films and we corroborate the results via comparison with space charge limited measurements. In summary, we demonstrate the potential of impedance spectroscopy to characterize key-to-photovoltaics optoelectronic properties, carrier lifetime, and mobility, in a facile way.

Reference: Arup K. Rath, Tania Lasanta, Maria Bernechea, Silke L. Diedenhofen, Gerasimos Konstantatos
Determination of carrier lifetime and mobility in colloidal quantum dot films via impedance spectroscopy
Appl. Phys. Lett. 104, 063504 (2014)