Lateral heterojunction photodetector consisting of molecular organic and colloidal quantum dot thin films

Publication Type:

Journal Article

Source:

Appl. Phys. Lett., AIP Publishing, Volume 94, Issue 4, p.043307 (2009)

ISBN:

0003-6951

Keywords:

2009, 2013 and earlier

Abstract:

We demonstrate a heterojunctionphotodetector of lateral geometry that utilizes an evaporated film of the hole-transporting molecular material N
, N ′ -bis(3-methylphenyl)- N , N ′ -bis(phenyl)-9,9-spirobifluorene
(spiro-TPD) as a charge transport layer and that is sensitized across
visible wavelengths by a thin film of colloidal CdSe nanocrystal quantum
dots(QDs). High photon-to-electron quantum conversion efficiencies are
obtained at room temperature as a result of photoconductive gain. With an
electric field of 3.0 × 10 5 V / cm applied across the electrodes, we
measure the external quantum efficiency at the first QDabsorption peak (at
wavelength λ = 590 nm ) to be 13%, corresponding to an internal quantum
efficiency of approximately 80%. The operating mechanism of these devices
is discussed, noting that the optical response is dominated by the
QDabsorptionspectrum while the charge transport nearly exclusively takes
place in the spiro-TPD.