Details

Autor(en) / Beteiligte

• Chen, Mengxue
• Liu, Dan
• Li, Wei
• Gurney, Robert S
• Li, Donghui
• Cai, Jinlong
• Spooner, Emma L. K
• Kilbride, Rachel C
• McGettrick, James D
• Watson, Trystan M
• Li, Zhe
• Jones, Richard A. L
• Lidzey, David G
• Wang, Tao

Titel

Influences of Non-fullerene Acceptor Fluorination on Three-Dimensional Morphology and Photovoltaic Properties of Organic Solar Cells

Ist Teil von

• ACS applied materials & interfaces, 2019-07, Vol.11 (29), p.26194-26203

Ort / Verlag

United States: American Chemical Society

Erscheinungsjahr

2019

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Fluorination of conjugated molecules has been established as an effective structural modification strategy to influence properties and has attracted extensive attention in organic solar cells (OSCs). Here, we have investigated optoelectronic and photovoltaic property changes of OSCs made of polymer donors with the non-fullerene acceptors (NFAs) ITIC and IEICO and their fluorinated counterparts IT-4F and IEICO-4F. Device studies show that fluorinated NFAs lead to reduced V oc but increased J sc and fill-factor (FF), and therefore, the ultimate influence to efficiency depends on the compensation of V oc loss and gains of J sc and FF. Fluorination lowers energy levels of NFAs, reduces their electronic band gaps, and red-shifts the absorption spectra. The impact of fluorination on the molecular order depends on the specific NFA, and the conversion of ITIC to IT-4F reduces the structural order, which can be reversed after blending with the donor PBDB-T. Contrastingly, IEICO-4F presents stronger π–π stacking after fluorination from IEICO, and this is further strengthened after blending with the donor PTB7-Th. The photovoltaic blends universally present a donor-rich surface region which can promote charge transport and collection toward the anode in inverted OSCs. The fluorination of NFAs, however, reduces the fraction of donors in this donor-rich region, consequently encouraging the intermixing of donor/acceptor for efficient charge generation.