{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,12]],"date-time":"2025-10-12T02:37:21Z","timestamp":1760236641458,"version":"build-2065373602"},"reference-count":32,"publisher":"MDPI AG","issue":"12","license":[{"start":{"date-parts":[[2021,12,12]],"date-time":"2021-12-12T00:00:00Z","timestamp":1639267200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Nanomaterials"],"abstract":"<jats:p>The impact of several solvent processing additives (1-chloronaphthalene, methylnaphthalene, hexadecane, 1-phenyloctane, and p-anisaldehyde), 3% v\/v in o-dichlorobenzene, on the performance and morphology of poly[(5,6-difluoro-2,1,3-benzothiadiazol-4,7-diyl)-alt-(3,3\u2034-di(2-octyldodecyl)-2,2\u2032,5\u2032,22033,5\u2033,2\u2034-quaterthiophen-5,5\u2034-diyl)] (PffBT4T-2OD):[6,6]-phenyl-C71-butyric acid methyl ester (PC71BM)-based polymer solar cells was investigated. Some additives were shown to enhance the power conversion efficiency (PCE) by ~6%, while others decreased the PCE by ~17\u201325% and a subset of the additives tested completely eliminated any power conversion efficiency and the operation as a photovoltaic device. Grazing-Incidence Wide Angle X-ray Scattering (GIWAXS) revealed a clear stepwise variation in the crystallinity of the systems when changing the additive between the two extreme situations of maximum PCE (1-chloronaphthalene) and null PCE (hexadecane). Small-Angle Neutron Scattering (SANS) revealed that the morphology of devices with PCE ~0% was composed of large domains with correlation lengths of ~30 nm, i.e., much larger than the typical exciton diffusion length (~12 nm) in organic semiconductors. The graded variations in crystallinity and in nano-domain size observed between the two extreme situations (1-chloronaphthalene and hexadecane) were responsible for the observed graded variations in device performance.<\/jats:p>","DOI":"10.3390\/nano11123367","type":"journal-article","created":{"date-parts":[[2021,12,13]],"date-time":"2021-12-13T01:29:33Z","timestamp":1639358973000},"page":"3367","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Graded Morphologies and the Performance of PffBT4T-2OD:PC71BM Devices Using Additive Choice"],"prefix":"10.3390","volume":"11","author":[{"given":"Hugo","family":"Gaspar","sequence":"first","affiliation":[{"name":"Institute for Polymers and Composites, University of Minho, 4800-058 Guimar\u00e3es, Portugal"},{"name":"LEPABE\u2014Laboratory for Process Engineering, Environment, Biotechnology and Energy, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal"}]},{"given":"Andrew J.","family":"Parnell","sequence":"additional","affiliation":[{"name":"Department of Physics and Astronomy, The University of Sheffield, Sheffield S3 7RH, UK"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3150-8467","authenticated-orcid":false,"given":"Gabriel E.","family":"P\u00e9rez","sequence":"additional","affiliation":[{"name":"Department of Chemical and Biological Engineering, The University of Sheffield, Sheffield S1 3JD, UK"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1210-2915","authenticated-orcid":false,"given":"J\u00falio C.","family":"Viana","sequence":"additional","affiliation":[{"name":"Institute for Polymers and Composites, University of Minho, 4800-058 Guimar\u00e3es, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3386-9151","authenticated-orcid":false,"given":"Stephen M.","family":"King","sequence":"additional","affiliation":[{"name":"ISIS Pulsed Neutron and Muon Source, STFC, Rutherford Appleton Laboratory, Harwell, Oxon OX11 0QX, UK"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2472-3265","authenticated-orcid":false,"given":"Ad\u00e9lio","family":"Mendes","sequence":"additional","affiliation":[{"name":"LEPABE\u2014Laboratory for Process Engineering, Environment, Biotechnology and Energy, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5482-0715","authenticated-orcid":false,"given":"Luiz","family":"Pereira","sequence":"additional","affiliation":[{"name":"Department of Physics and i3N\u2014Institute for Nanostructures, Nanomodelling and Nanofabrication, University of Aveiro, 3810-193 Aveiro, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7392-4915","authenticated-orcid":false,"given":"Gabriel","family":"Bernardo","sequence":"additional","affiliation":[{"name":"LEPABE\u2014Laboratory for Process Engineering, Environment, Biotechnology and Energy, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2021,12,12]]},"reference":[{"key":"ref_1","unstructured":"(2021, March 25). 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