Abstract
Organic indoor photovoltaics (OIPVs) for the development of a wireless power supplier that allows the portable operation of Internet-of-things and low-energy consumption devices have received tremendous interest. Particularly, polythiophene represented by poly(3-hexylthiophene) has been considered as a promising photoactive material for OIPVs owing to their desirable optoelectrical properties and power conversion efficiencies (PCEs) that exceed Si-based PVs under low-intensity illumination. However, the polythiophene-based OIPVs suffer from an inadequate charge transporting ability in the out-of-plane direction and a low open-circuit voltage (VOC), which currently hinder the further improvement of OIPVs. Herein, we designed and synthesized a new polythiophene derivative by combining fluorination and random copolymerization strategies. The optimized polymer obtained by tuning the ratio of fluorinated and non-fluorinated bi-thiophene units showed an increased population of face-on oriented crystallites, a denser packing, and a deeper highest occupied molecule orbital energy level compared with its homopolymer analogue. The optimized polymer was also revealed to provide improved vertical charge transport than homopolymer analogue. As a result, when fabricated using the phenyl-C71-butyric acid methyl ester as an electron-acceptor, the OIPVs with the optimized polymer showed high PCEs up to 13.4% with VOC of 0.68 V under 1000 lux white light-emitting diode illumination, which were improved values compared with the efficiencies observed in the devices with homopolymer (PCE = 5.6% and VOC = 0.57 V).
Original language | English |
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Article number | 109292 |
Journal | Dyes and Pigments |
Volume | 190 |
DOIs | |
State | Published - Jun 2021 |
Keywords
- Fluorinated conjugated polymer
- HOMO energy Level
- Indoor organic photovoltaics
- Polythiophene
- Random copolymerization
- Vertical charge transport