Efficient photon harvesting at high optical intensities in ultrathin organic double-heterostructure photovoltaic diodes

Publication Type:

Journal Article

Source:

Appl. Phys. Lett., AIP Publishing, Volume 76, Issue 19, p.2650-2652 (2000)

ISBN:

0003-6951

Keywords:

2000, 2013 and earlier

Abstract:

We demonstrate a method for efficient photon harvesting in organic thin films, thereby increasing the efficiency of organic photovoltaiccells. By
incorporating an exciton-blocking layer (EBL) inserted between the
photoactive organic layers and the metal cathode, we achieved an external
power conversion efficiency of 2.4%±0.3% in vacuum-deposited ultrathin
organic bilayer photovoltaic(PV)cells employed in a simple light trapping
geometry. Ultrathin (∼100 Å) cells incorporating the transparent,
conductive EBL have an internalquantum efficiency as high as 33%±4% over a
spectral region matched to the solar spectrum. The very thin organic
layers have a low series resistance, allowing for efficient power
conversion in organic PVcells under intense (>15 suns) AM1.5 illumination.
This device structure demonstrates that control of exciton diffusion in
solid-state organic devices leads to a significant increase in the
photon-to-carrier conversion efficiency.