{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,12]],"date-time":"2025-10-12T04:27:42Z","timestamp":1760243262427,"version":"build-2065373602"},"reference-count":22,"publisher":"MDPI AG","issue":"12","license":[{"start":{"date-parts":[[2014,12,22]],"date-time":"2014-12-22T00:00:00Z","timestamp":1419206400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Materials"],"abstract":"<jats:p>We report on the efficiency improvement of organic solar cells (OPVs) based on the low energy gap polyfluorene derivative, APFO-3, and the soluble C60 fullerene PCBM, upon addition of a residual amount of poly (4-vinylpyridine) (PVP). We find that the addition of 1% by weight of PVP with respect to the APFO-3 content leads to an increase of efficiency from 2.4% to 2.9%. Modifications in the phase separation details of the active layer were investigated as a possible origin of the efficiency increase. At high concentrations of PVP, the blend morphology is radically altered as observed by Atomic Force Microscopy. Although the use of low molecular weight additives is a routine method to improve OPVs efficiency, this report shows that inert polymers, in terms of optical and charge transport properties, may also improve the performance of polymer-based solar cells.<\/jats:p>","DOI":"10.3390\/ma7128189","type":"journal-article","created":{"date-parts":[[2014,12,22]],"date-time":"2014-12-22T08:31:01Z","timestamp":1419237061000},"page":"8189-8196","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":5,"title":["Improving the Efficiency of Organic Solar Cells upon Addition of Polyvinylpyridine"],"prefix":"10.3390","volume":"7","author":[{"given":"Rita","family":"Rodrigues","sequence":"first","affiliation":[{"name":"Instituto de Telecomunica\u00e7\u00f5es, Avenida Rovisco Pais, P-1049-001 Lisboa, Portugal"}]},{"given":"Rui","family":"Meira","sequence":"additional","affiliation":[{"name":"Instituto de Telecomunica\u00e7\u00f5es, Avenida Rovisco Pais, P-1049-001 Lisboa, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7541-3104","authenticated-orcid":false,"given":"Quirina","family":"Ferreira","sequence":"additional","affiliation":[{"name":"Instituto de Telecomunica\u00e7\u00f5es, Avenida Rovisco Pais, P-1049-001 Lisboa, Portugal"}]},{"given":"Ana","family":"Charas","sequence":"additional","affiliation":[{"name":"Instituto de Telecomunica\u00e7\u00f5es, Avenida Rovisco Pais, P-1049-001 Lisboa, Portugal"}]},{"given":"Jorge","family":"Morgado","sequence":"additional","affiliation":[{"name":"Instituto de Telecomunica\u00e7\u00f5es, Avenida Rovisco Pais, P-1049-001 Lisboa, Portugal"},{"name":"Department of Bioengineering, Instituto Superior T\u00e9cnico, UL, Avenida Rovisco Pais,  P-1049-001 Lisboa, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2014,12,22]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"911","DOI":"10.1038\/nature02498","article-title":"The path to ubiquitous and low-cost organic electronic appliances on plastic","volume":"428","author":"Forrest","year":"2004","journal-title":"Nature"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"251","DOI":"10.1039\/b812502n","article-title":"Organic photovoltaics","volume":"2","author":"Kippelen","year":"2009","journal-title":"Energy Environ. Sci."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"775","DOI":"10.1016\/j.orgel.2008.05.021","article-title":"Substituting the postproduction treatment for bulk-heterojunction solar cells using chemical additives","volume":"9","author":"Pivrikas","year":"2008","journal-title":"Org. Electron."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"44","DOI":"10.1038\/nmat3160","article-title":"Solution-processed small-molecule solar cells with 6.7% efficiency","volume":"11","author":"Sun","year":"2012","journal-title":"Nat. Mater."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"1521","DOI":"10.1016\/S0379-6779(02)01218-3","article-title":"Improvement of the performance of polymer\/C60 photovoltaic cells by small-molecule doping","volume":"137","author":"Yang","year":"2003","journal-title":"Synth. Met."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"3619","DOI":"10.1021\/ja710079w","article-title":"Processing additives for improved efficiency from bulk heterojunction solar cells","volume":"130","author":"Lee","year":"2008","journal-title":"J. Am. Chem. Soc."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"1226","DOI":"10.1016\/j.solener.2010.10.012","article-title":"Influence of processing additives to nano-morphology and efficiency of bulk-heterojunction solar cells: A comparative review","volume":"85","author":"Pivrikas","year":"2011","journal-title":"Sol. Energy"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"4168","DOI":"10.1002\/adma.201400497","article-title":"High-molecular-weight insulating polymers can improve the performance of molecular solar cells","volume":"26","author":"Huang","year":"2014","journal-title":"Adv. Mater."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"137","DOI":"10.1016\/S0379-6779(02)00552-0","article-title":"Synthesis and properties of alternating polyfluorene copolymers with redshift absorption for use in solar cells","volume":"135","author":"Svensson","year":"2003","journal-title":"Synth. Met."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"988","DOI":"10.1002\/adma.200304150","article-title":"High-performance polymer solar cells of an alternating polyfluorene copolymer and a fullerene derivative","volume":"15","author":"Svensson","year":"2003","journal-title":"Adv. Mater."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"E135","DOI":"10.1002\/adma.200903528","article-title":"For the bright future-Bulk heterojunction polymer solar cells with power conversion efficiency of 7.4%","volume":"22","author":"Liang","year":"2010","journal-title":"Adv. Mater."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"5330","DOI":"10.1021\/ja101888b","article-title":"A thieno[3,4-c]pyrrole-4,6-dione-based copolymer for efficient solar cells","volume":"132","author":"Zou","year":"2010","journal-title":"J. Am. Chem. Soc."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"109","DOI":"10.1016\/j.synthmet.2005.07.195","article-title":"Control of phase separation in blends of polyfluorene (co)polymers and the C60-derivative PCBM","volume":"152","author":"Bjorstrom","year":"2005","journal-title":"Synth. Met."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"8291","DOI":"10.1021\/ma070712a","article-title":"Morphology and phase segregation of spin-casted films of polyfluorene\/PCBM blends","volume":"40","author":"Nilsson","year":"2007","journal-title":"Macromolecules"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"829","DOI":"10.1002\/1521-3927(20010701)22:11<829::AID-MARC829>3.0.CO;2-8","article-title":"Three-dimensional information on the phase domain structure of thin films of polymer blends revealed by secondary ion mass spectrometry","volume":"22","author":"Bernasik","year":"2001","journal-title":"Macromol. Rapid Commun."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"8486","DOI":"10.1021\/ma051242s","article-title":"Composition effects in polymer blends spin-cast on patterned substrates","volume":"38","author":"Raczkowska","year":"2005","journal-title":"Macromolecules"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"L529","DOI":"10.1088\/0953-8984\/17\/50\/L01","article-title":"Multilayer formation in spin-coated thin films of low-bandgap polyfluorene:PCBM blends","volume":"17","author":"Bernasik","year":"2005","journal-title":"J. Phys. Condens. Matter"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"4398","DOI":"10.1002\/adma.200900754","article-title":"Device performance of APFO-3\/PCBM solar cells with controlled morphology","volume":"21","author":"Rysz","year":"2009","journal-title":"Adv. Mater."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"6849","DOI":"10.1063\/1.1620683","article-title":"Cathode dependence of the open-circuit voltage of polymer:fullerene bulk heterojunction solar cells","volume":"94","author":"Mihailetchi","year":"2003","journal-title":"J. Appl. Phys."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"083708","DOI":"10.1063\/1.3246786","article-title":"Adhesion in organic electronic structures","volume":"106","author":"Tong","year":"2009","journal-title":"J. Appl. Phys."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"745","DOI":"10.1007\/s003960100485","article-title":"Electroless deposition of copper on polyimide films modified by surface graft copolymerization with nitrogen-containing vinyl monomers","volume":"279","author":"Yang","year":"2001","journal-title":"Colloid Polym. Sci."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"471","DOI":"10.1016\/S0143-7496(02)00057-X","article-title":"Thermal graft copolymerization of 4-vinyl pyridine on polyimide to improve adhesion to copper","volume":"22","author":"Tan","year":"2002","journal-title":"Int. J. Adhesi. Adhesi."}],"container-title":["Materials"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1996-1944\/7\/12\/8189\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T21:11:28Z","timestamp":1760217088000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1996-1944\/7\/12\/8189"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2014,12,22]]},"references-count":22,"journal-issue":{"issue":"12","published-online":{"date-parts":[[2014,12]]}},"alternative-id":["ma7128189"],"URL":"https:\/\/doi.org\/10.3390\/ma7128189","relation":{},"ISSN":["1996-1944"],"issn-type":[{"type":"electronic","value":"1996-1944"}],"subject":[],"published":{"date-parts":[[2014,12,22]]}}}