The Impact of Sequential Fluorination of [pi]-Conjugated Polymers on Charge Generation in All-Polymer Solar Cells

The performance of all-polymer solar cells (all-PSCs) is often limited by the poor exciton dissociation process. Here, the design of a series of polymer donors (P1-P3) with different numbers of fluorine atoms on their backbone is presented and the influence of fluorination on charge generation in al...

Full description

Saved in:
Bibliographic Details
Published inAdvanced functional materials Vol. 27; no. 29
Main Authors Kranthiraja, Kakaraparthi, Kim, Seonha, Lee, Changyeon, Gunasekar, Kumarasamy, Sree, Vijaya Gopalan, Gautam, Bhoj, Gundogdu, Kenan, Jin, Sung-Ho, Kim, Bumjoon J
Format Journal Article
LanguageEnglish
Published Hoboken Wiley Subscription Services, Inc 01.08.2017
Subjects
Current density
Dipole moments
Energy conversion efficiency
Fluorination
Fluorine
Luminous intensity
Materials science
Photoluminescence
Photovoltaic cells
Polyimide resins
Polymers
Service life assessment
Short circuits
Solar cells
Online AccessGet full text

Cover

More Information
Summary:The performance of all-polymer solar cells (all-PSCs) is often limited by the poor exciton dissociation process. Here, the design of a series of polymer donors (P1-P3) with different numbers of fluorine atoms on their backbone is presented and the influence of fluorination on charge generation in all-PSCs is investigated. Sequential fluorination of the polymer backbones increases the dipole moment difference between the ground and excited states ([Delta]µge) from P1 (18.40 D) to P2 (25.11 D) and to P3 (28.47 D). The large [Delta]µge of P3 leads to efficient exciton dissociation with greatly suppressed charge recombination in P3-based all-PSCs. Additionally, the fluorination lowers the highest occupied molecular orbital energy level of P3 and P2, leading to higher open-circuit voltage (VOC). The power conversion efficiency of the P3-based all-PSCs (6.42%) outperforms those of the P2 and P1 (5.00% and 2.65%)-based devices. The reduced charge recombination and the enhanced polymer exciton lifetime in P3-based all-PSCs are confirmed by the measurements of light-intensity dependent short-circuit current density (JSC) and VOC, and time-resolved photoluminescence. The results provide reciprocal understanding of the charge generation process associated with [Delta]µge in all-PSCs and suggest an effective strategy for designing π-conjugated polymers for high performance all-PSCs.
ISSN:1616-301X
1616-3028
DOI:10.1002/adfm.201701256