Microlens array induced light absorption enhancement in polymer solar cells

TitleMicrolens array induced light absorption enhancement in polymer solar cells
Publication TypeJournal Article
Year of Publication2013
AuthorsChen YQ, Elshobaki M, Ye Z, Park JM, Noack MA, Ho KM, Chaudhary S
Journal TitlePhysical Chemistry Chemical Physics
Volume15
Pages4297-4302
Date Published03/28
Type of ArticleArticle
ISBN Number1463-9076
Accession NumberWOS:000315411200028
Keywordsbandgap polymers, blends, diffusion, EFFICIENCY, morphology evolution
Abstract

Over the last decade, polymer solar cells (PSCs) have attracted a lot of attention and highest power conversion efficiencies (PCE) are now close to 10%. Here we employ an optical structure - the microlens array (MLA) - to increase light absorption inside the active layer, and PCE of PSCs increased even for optimized devices. Normal incident light rays are refracted at the MLA and travel longer optical paths inside the active layers. Two PSC systems - poly(3-hexylthiophene-2,5-diyl):(6,6)-phenyl C61 butyric acid methyl ester (P3HT:PCBM) and poly[[9-(1-octylnonyl)-9H-carbazole-2,7-diyl]-2,5-thiophenediyl-2,1,3-benzothiadiazole-4,7-diyl-2,5-thiophenediyl]:(6,6)-phenyl C71 butyric acid methyl ester (PCDTBT:PC70BM) - were investigated. In the P3HT:PCBM system, MLA increased the absorption, absolute external quantum efficiency, and the PCE of an optimized device by similar to 4.3%. In the PCDTBT:PC70BM system, MLA increased the absorption, absolute external quantum efficiency, and PCE by more than 10%. In addition, simulations incorporating optical parameters of all structural layers were performed and they support the enhancement of absorption in the active layer with the assistance of MLA. Our results show that utilizing MLA is an effective strategy to further increase light absorption in PSCs, in which optical losses account for similar to 40% of total losses. MLA also does not pose materials processing challenges to the active layers since it is on the other side of the transparent substrate.

URL<Go to ISI>://WOS:000315411200028
DOI10.1039/c3cp50297j