Cathode dependence of the open-circuit voltage of polymer:fullerene bulk heterojunction solar cells
Year: 2003
Type: article
Abstract: The open-circuit voltage (VOC) of bulk-heterojunction solar cells based on [6,6]-phenyl C61-butyric acid methyl ester (PCBM) as electron acceptor and poly[2-methoxy-5(3′,7′-dimethyloctyloxy)-p-phenylene vinylene] (OC1C10-PPV) as an electron donor has been investigated. In contrast to the present understanding, it is now demonstrated that for non-ohmic contacts the experimental VOC is determined by the work function difference of the electrodes. A total variation of more than 0.5 V of the VOC was observed by variation of the negative electrode (cathode) work function. For ohmic contacts the VOC is governed by the LUMO and HOMO levels of the acceptor and donor, respectively, which pin the Fermi levels of the cathode and anode. The band bending created by accumulated charges at an ohmic contact produce a considerable loss in VOC of 0.2 V at room temperature. The experimentally observed voltage loss in VOC of 0.38 V due to the presence of ohmic contacts at both interfaces strongly limits the maximum open-circuit voltage of OC1C10-PPV/PCBM solar cells.
Source: Journal of Applied Physics
DOI: 10.1063/1.1620683
Institution: University of Groningen
Language: English
Subfield: Electrical and Electronic Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W2019310480