Jump to main content
Jump to site search


Optimum driving energy for achieving balanced open circuit voltage and short circuit current density in organic bulk heterojunction solar cells

Abstract

The organic bulk heterojunction solar cells generally suffer from a trade off between the open circuit voltage (Voc) and the short circuit current density (Jsc) under a given donor/acceptor (D/A) interfacial energetic offset (or the so-called driving force). Here we theoretically investigate the optimum driving energy required for achieving the balanced Jsc and Voc simultaneously. To this end, the Jsc versus the driving force ΔE curves are calculated under two different charge separation mechanisms by employing the drift-diffusion method. For the Marcus incoherent mechanism, the curve features a high plateau in a broad range of ΔE starting from 0.2 eV, which is due to the accumulation of undissociated excitons within their lifetime and signifies the possibility of obtaining a sizable Jsc under a ΔE much smaller than the reorganization energy. After incorporating both the electron and hole transfer pathways into the device model, the calculated J-V curves are comparable to experimentally measured ones corresponding to actual blended systems of different driving forces. For the coherent mechanism, it is demonstrated that the maximum Jsc can also be achieved under the ΔE of 0.2 eV if large proportion of the high-lying delocalized states are harvested through tuning the density of states for the charge transfer excitons to reduce the sub-gap states. This theoretical work revealed the relationship between the interfacial energy offsets and the device performance, and also provide some guidelines for identifying the macroscopic features of the actual charge separation mechanisms in bulk heterojunction solar cells.

Back to tab navigation

Publication details

The article was received on 13 Aug 2018, accepted on 06 Nov 2018 and first published on 07 Nov 2018


Article type: Paper
DOI: 10.1039/C8CP05145C
Citation: Phys. Chem. Chem. Phys., 2018, Accepted Manuscript
  •   Request permissions

    Optimum driving energy for achieving balanced open circuit voltage and short circuit current density in organic bulk heterojunction solar cells

    W. Yang, Y. Yao, P. Guo, H. sun and Y. Luo, Phys. Chem. Chem. Phys., 2018, Accepted Manuscript , DOI: 10.1039/C8CP05145C

Search articles by author

Spotlight

Advertisements