An ethanolamine (ETA)-functionalized fullerene (C60-ETA) was synthesized by using a facile one-pot addition reaction, and applied as an efficient electron transport layer (ETL) for inverted polymer solar cells (iPSCs) with the efficiency exceeding 9.5%, which represents the highest power conversion efficiency (PCE) reported so far for iPSC devices with independent fullerene derivative ETLs. The chemical structure of C60-ETA was studied by FT-IR and XPS spectroscopies and elemental analysis, and the average molecular formula of C60-ETA is estimated to be C60(NHC2H4OH)8(H)8 with an average ETA addition number of eight. C60-ETA was applied as an ETL for bulk heterojunction (BHJ) iPSC devices based on different photoactive layers including poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b′]dithiophene-co-3-fluorothieno[3,4-b]thiophene-2-carboxylate]:[6,6]-phenyl C71-butyric acid methyl ester (PTB7-Th:PC71BM), poly(4,8-bis-alkyloxybenzo(l,2-b:4,5-b′)dithiophene-2,6-diylalt-(alkyl thieno(3,4-b)thiophene-2-carboxylate)-2,6-diyl) (PBDTTT-C):PC71BM and poly(3-hexylthiophene-2,5-diyl):[6,6]-phenyl C61-butyric acid methyl ester (P3HT:PC61BM), leading to the best PCE of 9.55%, 6.50% and 4.18%, respectively, which are all higher than those of the corresponding reference devices based on the ZnO ETL. The PCE improvement of the C60-ETA device relative to that of the ZnO device primarily originates from the increase of short-circuit current density (Jsc), which is due to the smoothened ETL surface and the increase of electron mobility, facilitating electron transport from the active layer to the ITO cathode.
ASJC Scopus subject areas
- Renewable Energy, Sustainability and the Environment
- Materials Science(all)