{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,4]],"date-time":"2026-06-04T15:14:30Z","timestamp":1780586070636,"version":"3.54.1"},"reference-count":68,"publisher":"Wiley","issue":"5","license":[{"start":{"date-parts":[[2026,5,15]],"date-time":"2026-05-15T00:00:00Z","timestamp":1778803200000},"content-version":"vor","delay-in-days":14,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"},{"start":{"date-parts":[[2026,5,1]],"date-time":"2026-05-01T00:00:00Z","timestamp":1777593600000},"content-version":"tdm","delay-in-days":0,"URL":"http:\/\/doi.wiley.com\/10.1002\/tdm_license_1.1"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Small Science"],"published-print":{"date-parts":[[2026,5]]},"abstract":"<jats:p>The design of vacuum\u2010processed organic solar cells requires a balance between optimizing energetic and morphological properties for efficient photovoltaic performance. In this study, we investigate two structurally similar molecular donors, DCV\u2010iPr and DCV\u2010Me, which exhibit stark differences in photovoltaic performance despite their minimal chemical differences. Through a combined experimental and theoretical approach\u2014including crystal structure prediction, vapor deposition simulations, GIWAXS measurements, and advanced electronic structure calculations\u2014we establish how molecular packing influences optical absorption and photovoltaic efficiency. Our findings show that steric effects introduced by the isopropyl group in DCV\u2010iPr lead to a brick\u2010wall molecular arrangement, favoring J\u2010like excitonic interactions and resulting in sharp optical absorption with a reduced Stokes shift. In contrast, DCV\u2010Me forms a more H\u2010like aggregation, leading to broadened absorption and higher voltage losses. While DCV\u2010iPr demonstrates enhanced photovoltaic performance, we identify substantial remaining voltage losses associated with charge\u2013transfer excitations at the donor\u2013acceptor interface. This work provides key design guidelines linking molecular packing to optical absorption properties and highlights the need for alternative acceptor materials with steeper absorption onsets to further optimize vacuum\u2010processed organic solar cells.<\/jats:p>","DOI":"10.1002\/smsc.202500633","type":"journal-article","created":{"date-parts":[[2026,5,15]],"date-time":"2026-05-15T20:13:31Z","timestamp":1778876011000},"source":"Crossref","is-referenced-by-count":0,"title":["On the Design of Steep Optical Absorbers for Vacuum\u2010Processed Organic Solar Cells: One Isopropyl Group Makes the Difference"],"prefix":"10.1002","volume":"6","author":[{"ORCID":"https:\/\/orcid.org\/0009-0004-4748-1902","authenticated-orcid":false,"given":"Mohamed el habib","family":"Bouajhine","sequence":"first","affiliation":[{"name":"Laboratory for Chemistry of Novel Materials University of Mons  Mons Belgium"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3405-2701","authenticated-orcid":false,"given":"Emilio","family":"Lorini","sequence":"additional","affiliation":[{"name":"Department of Industrial Chemistry University of Bologna  Bologna Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1094-3921","authenticated-orcid":false,"given":"Samuele","family":"Giannini","sequence":"additional","affiliation":[{"name":"Department of Chemistry and Industrial Chemistry University of Pisa  Pisa Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7004-818X","authenticated-orcid":false,"given":"Siebe","family":"Frederix","sequence":"additional","affiliation":[{"name":"imec, Institute for Materials Research (imo\u2010imomec) Hasselt University  Diepenbeek Belgium"},{"name":"imo\u2010imomec Energyville  Genk Belgium"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Karsten","family":"Walzer","sequence":"additional","affiliation":[{"name":"Heliatek GmbH  Dresden Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Marieta","family":"Levichkova","sequence":"additional","affiliation":[{"name":"Heliatek GmbH  Dresden Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Gunter","family":"Mattersteig","sequence":"additional","affiliation":[{"name":"Heliatek GmbH  Dresden Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Martin","family":"Pfeiffer","sequence":"additional","affiliation":[{"name":"Heliatek GmbH  Dresden Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Eva","family":"Bittrich","sequence":"additional","affiliation":[{"name":"Leibniz\u2010Institut f\u00fcr Polymerforschung Dresden e.V.  Dresden Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9298-4083","authenticated-orcid":false,"given":"Petra","family":"Uhlmann","sequence":"additional","affiliation":[{"name":"Leibniz\u2010Institut f\u00fcr Polymerforschung Dresden e.V.  Dresden Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8601-286X","authenticated-orcid":false,"given":"Vincent","family":"Lemaur","sequence":"additional","affiliation":[{"name":"Laboratory for Chemistry of Novel Materials University of Mons  Mons Belgium"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5471-383X","authenticated-orcid":false,"given":"Koen","family":"Vandewal","sequence":"additional","affiliation":[{"name":"imec, Institute for Materials Research (imo\u2010imomec) Hasselt University  Diepenbeek Belgium"},{"name":"imo\u2010imomec Energyville  Genk Belgium"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9006-3635","authenticated-orcid":false,"given":"Patrick","family":"Brocorens","sequence":"additional","affiliation":[{"name":"Laboratory for Chemistry of Novel Materials University of Mons  Mons Belgium"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9227-1059","authenticated-orcid":false,"given":"Luca","family":"Muccioli","sequence":"additional","affiliation":[{"name":"Department of Industrial Chemistry University of Bologna  Bologna Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5082-9990","authenticated-orcid":false,"given":"David","family":"Beljonne","sequence":"additional","affiliation":[{"name":"Laboratory for Chemistry of Novel Materials University of Mons  Mons Belgium"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"311","published-online":{"date-parts":[[2026,5,15]]},"reference":[{"key":"e_1_2_9_2_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.dibe.2025.100607"},{"key":"e_1_2_9_3_1","volume-title":"WHITEPAPER: \u201cOrganic Photovoltaics \u2013 Truly Green Energy: Ultra\u2010Low Carbon Footprint","year":"2020"},{"key":"e_1_2_9_4_1","doi-asserted-by":"publisher","DOI":"10.1002\/aenm.202002653"},{"key":"e_1_2_9_5_1","doi-asserted-by":"publisher","DOI":"10.1038\/s41563-022-01244-y"},{"key":"e_1_2_9_6_1","doi-asserted-by":"publisher","DOI":"10.1038\/s41563-024-02087-5"},{"key":"e_1_2_9_7_1","doi-asserted-by":"publisher","DOI":"10.1002\/anie.202404297"},{"key":"e_1_2_9_8_1","doi-asserted-by":"publisher","DOI":"10.1002\/pip.3867"},{"key":"e_1_2_9_9_1","doi-asserted-by":"publisher","DOI":"10.1088\/2515-7655\/ad7404"},{"key":"e_1_2_9_10_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.progpolymsci.2019.02.002"},{"key":"e_1_2_9_11_1","unstructured":"Heliatek GmbH Certificate No. PV 60176081 T\u00dcV Reinland 2024 https:\/\/www.certipedia.com\/certificates\/60176081?locale=en."},{"key":"e_1_2_9_12_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.scib.2025.01.004"},{"key":"e_1_2_9_13_1","unstructured":"O. L.Griffith X.Liu J. A.Amonoo et al. Charge Transport and Exciton Dissociation in Organic Solar Cells Consisting of Dipolar Donors Mixed with C70 085404 2015 1\u20139."},{"key":"e_1_2_9_14_1","doi-asserted-by":"crossref","unstructured":"X.Che C.Chung C.Hsu F.Liu K.Wong andS. R.Forrest Donor \u2013 Acceptor \u2013 Acceptor's Molecules for Vacuum\u2010Deposited Organic Photovoltaics with Efficiency Exceeding 9% 1703603 2018 1\u20136.","DOI":"10.1002\/aenm.201703603"},{"key":"e_1_2_9_15_1","doi-asserted-by":"publisher","DOI":"10.1038\/nenergy.2017.53"},{"key":"e_1_2_9_16_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.trechm.2019.01.010"},{"key":"e_1_2_9_17_1","first-page":"1","article-title":"Non\u2010Radiative Recombination Energy Losses in Non\u2010Fullerene Organic Solar Cells","volume":"32","author":"He D.","year":"2022","journal-title":"Advanced Functional Materials"},{"key":"e_1_2_9_18_1","doi-asserted-by":"publisher","DOI":"10.1021\/acs.chemrev.7b00581"},{"key":"e_1_2_9_19_1","doi-asserted-by":"publisher","DOI":"10.1021\/ar900233v"},{"key":"e_1_2_9_20_1","doi-asserted-by":"publisher","DOI":"10.1039\/D4TC01716A"},{"key":"e_1_2_9_21_1","doi-asserted-by":"publisher","DOI":"10.1038\/s41563-018-0128-z"},{"key":"e_1_2_9_22_1","doi-asserted-by":"publisher","DOI":"10.1021\/acs.jpclett.3c00021"},{"key":"e_1_2_9_23_1","doi-asserted-by":"publisher","DOI":"10.1021\/acsenergylett.2c00816"},{"key":"e_1_2_9_24_1","doi-asserted-by":"publisher","DOI":"10.1038\/s41467-021-24202-9"},{"key":"e_1_2_9_25_1","doi-asserted-by":"publisher","DOI":"10.1021\/ja302320c"},{"key":"e_1_2_9_26_1","doi-asserted-by":"publisher","DOI":"10.1002\/adts.202300080"},{"key":"e_1_2_9_27_1","doi-asserted-by":"publisher","DOI":"10.1002\/adfm.201402609"},{"key":"e_1_2_9_28_1","doi-asserted-by":"publisher","DOI":"10.1002\/adma.201101652"},{"key":"e_1_2_9_29_1","doi-asserted-by":"publisher","DOI":"10.1002\/jcc.27027"},{"key":"e_1_2_9_30_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.mattod.2024.09.009"},{"key":"e_1_2_9_31_1","doi-asserted-by":"publisher","DOI":"10.1002\/adfm.201503888"},{"key":"e_1_2_9_32_1","doi-asserted-by":"publisher","DOI":"10.1021\/acs.accounts.0c00349"},{"key":"e_1_2_9_33_1","doi-asserted-by":"publisher","DOI":"10.1021\/cr9904009"},{"key":"e_1_2_9_34_1","doi-asserted-by":"publisher","DOI":"10.1002\/adma.200801668"},{"key":"e_1_2_9_35_1","doi-asserted-by":"publisher","DOI":"10.1039\/C7CP07002K"},{"key":"e_1_2_9_36_1","doi-asserted-by":"publisher","DOI":"10.1007\/s11120-018-0492-1"},{"key":"e_1_2_9_37_1","doi-asserted-by":"publisher","DOI":"10.1063\/5.0022677"},{"key":"e_1_2_9_38_1","doi-asserted-by":"publisher","DOI":"10.1038\/s41467-022-30308-5"},{"key":"e_1_2_9_39_1","doi-asserted-by":"publisher","DOI":"10.1021\/acs.jpclett.1c02275"},{"key":"e_1_2_9_40_1","doi-asserted-by":"publisher","DOI":"10.1039\/C5TC03283K"},{"key":"e_1_2_9_41_1","doi-asserted-by":"publisher","DOI":"10.1021\/acs.jpclett.0c02858"},{"key":"e_1_2_9_42_1","doi-asserted-by":"publisher","DOI":"10.1088\/0953-8984\/28\/43\/433002"},{"key":"e_1_2_9_43_1","doi-asserted-by":"publisher","DOI":"10.1021\/ct500618w"},{"key":"e_1_2_9_44_1","doi-asserted-by":"publisher","DOI":"10.1038\/nmat2548"},{"key":"e_1_2_9_45_1","doi-asserted-by":"publisher","DOI":"10.1039\/C7SE00601B"},{"key":"e_1_2_9_46_1","doi-asserted-by":"publisher","DOI":"10.1103\/PhysRevB.81.125204"},{"key":"e_1_2_9_47_1","doi-asserted-by":"publisher","DOI":"10.1021\/jacs.7b07887"},{"key":"e_1_2_9_48_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.joule.2021.06.006"},{"key":"e_1_2_9_49_1","doi-asserted-by":"publisher","DOI":"10.1039\/D5SC06155E"},{"key":"e_1_2_9_50_1","doi-asserted-by":"publisher","DOI":"10.1016\/j.mser.2025.101144"},{"key":"e_1_2_9_51_1","doi-asserted-by":"publisher","DOI":"10.1002\/adfm.202421048"},{"key":"e_1_2_9_52_1","doi-asserted-by":"publisher","DOI":"10.1039\/C6EE02100J"},{"key":"e_1_2_9_53_1","doi-asserted-by":"publisher","DOI":"10.1021\/acs.jcim.5c00669"},{"key":"e_1_2_9_54_1","doi-asserted-by":"publisher","DOI":"10.1038\/nnano.2011.145"},{"key":"e_1_2_9_55_1","doi-asserted-by":"publisher","DOI":"10.1107\/S2052252514024178"},{"key":"e_1_2_9_56_1","unstructured":"BIOVIA Dassault Syst\u00e8mes Material Studio 2022 (22.1.0.3462 Version) https:\/\/www.3ds.com\/it\/products\/biovia."},{"key":"e_1_2_9_57_1","doi-asserted-by":"publisher","DOI":"10.1021\/j100389a010"},{"key":"e_1_2_9_58_1","doi-asserted-by":"publisher","DOI":"10.1021\/acs.chemmater.9b01286"},{"key":"e_1_2_9_59_1","doi-asserted-by":"publisher","DOI":"10.1002\/adts.201800089"},{"key":"e_1_2_9_60_1","doi-asserted-by":"publisher","DOI":"10.1103\/PhysRevLett.102.073005"},{"key":"e_1_2_9_61_1","doi-asserted-by":"publisher","DOI":"10.1063\/5.0014475"},{"key":"e_1_2_9_62_1","unstructured":"E.Lorini MYTHOS n.d.https:\/\/gitlab.com\/emilio.lorini\/MYTHOS."},{"key":"e_1_2_9_63_1","doi-asserted-by":"publisher","DOI":"10.1063\/1.464397"},{"key":"e_1_2_9_64_1","doi-asserted-by":"publisher","DOI":"10.1021\/acs.jctc.0c00919"},{"key":"e_1_2_9_65_1","unstructured":"A. J.Sneyd T.Fukui D.Palecek et al. Highly Efficient Exciton Transport via Transient Delocalization in Films of Poly(3\u2010Hexylthiophene) Nanofibers Prepared by Seeded Growth 2020."},{"key":"e_1_2_9_66_1","doi-asserted-by":"publisher","DOI":"10.1021\/acs.jpclett.2c01133"},{"key":"e_1_2_9_67_1","doi-asserted-by":"publisher","DOI":"10.1002\/wcms.1392"},{"key":"e_1_2_9_68_1","doi-asserted-by":"publisher","DOI":"10.1021\/jp0615398"},{"key":"e_1_2_9_69_1","first-page":"1","article-title":"Charge Generation in Organic Solar Cells: Journey toward 20% Power Conversion Efficiency","volume":"3","author":"Tamai Y.","year":"2022","journal-title":"Aggregate"}],"container-title":["Small Science"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/onlinelibrary.wiley.com\/doi\/pdf\/10.1002\/smsc.202500633","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/onlinelibrary.wiley.com\/doi\/full-xml\/10.1002\/smsc.202500633","content-type":"application\/xml","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/onlinelibrary.wiley.com\/doi\/pdf\/10.1002\/smsc.202500633","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,6,4]],"date-time":"2026-06-04T14:54:16Z","timestamp":1780584856000},"score":1,"resource":{"primary":{"URL":"https:\/\/onlinelibrary.wiley.com\/doi\/10.1002\/smsc.202500633"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,5]]},"references-count":68,"journal-issue":{"issue":"5","published-print":{"date-parts":[[2026,5]]}},"alternative-id":["10.1002\/smsc.202500633"],"URL":"https:\/\/doi.org\/10.1002\/smsc.202500633","archive":["Portico"],"relation":{},"ISSN":["2688-4046","2688-4046"],"issn-type":[{"value":"2688-4046","type":"print"},{"value":"2688-4046","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,5]]},"article-number":"e202500633"}}