Issue 41, 2015

Origin of photogenerated carrier recombination at the metal–active layer interface in polymer solar cells

Abstract

The role of the metal–active layer interface in photogenerated recombination has been investigated using nanoscale current sensing atomic force microscopy (CS-AFM) and intensity modulated photocurrent spectroscopy (IMPS) in as-deposited, pre-annealed and post-annealed bulk heterojunction (BHJ) solar cells. Aluminum (Al) confined post-annealed BHJ solar cells exhibited a significantly improved device efficiency compared to pre-annealed BHJ solar cells having similar photocarrier harvesting ability in the active layer. The nanoscale topography and CS-AFM results indicate a uniform PCBM rich phase at the metal–active layer interface in the post-annealed cells, but PCBM segregation in the pre-annealed cells. These two different annealing processes showed different carrier dynamics revealed using IMPS under various light intensities. The IMPS results suggest reduced photo generated carrier recombination in uniform PCBM rich post-annealed BHJ solar cells. This study reveals the importance of the metal–bend interface in BHJ solar cells in order to obtain efficient charge carrier extraction for high efficiency.

Graphical abstract: Origin of photogenerated carrier recombination at the metal–active layer interface in polymer solar cells

Article information

Article type
Paper
Submitted
14 Aug 2015
Accepted
23 Sep 2015
First published
25 Sep 2015

Phys. Chem. Chem. Phys., 2015,17, 27690-27697

Origin of photogenerated carrier recombination at the metal–active layer interface in polymer solar cells

M. Kumar, A. Dubey, K. M. Reza, N. Adhikari, Q. Qiao and V. Bommisetty, Phys. Chem. Chem. Phys., 2015, 17, 27690 DOI: 10.1039/C5CP04831A

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