Comparative Study of Selenophene- and Thiophene-Containing n-Type Semiconducting Polymers for High Performance All-Polymer Solar Cells

Abstract

Effects of the donor moiety substitution on the intrinsic and photovoltaic blend properties of n-type semiconducting naphthalene diimide-arylene copolymers with donor−acceptor structure were investigated. The alternating naphthalene diimide-thiophene copolymer, PNDIT-hd, and naphthalene diimide-selenophene copolymer, PNDIS-hd, were found to have identical electrochemically derived electronic structures and similar bulk electron mobility; however, PNDIShd has an optical bandgap of 1.70 eV, which is 0.07 eV narrower relative to that of PNDIT-hd. All-polymer solar cells incorporating the donor polymer, PBDB-T, and PNDIS-hd were found to combine a high power conversion efficiency of 8.4% with high external quantum efficiency (86%) and a high fill factor of 0.71, which are significantly enhanced compared to the corresponding PBDB-T:PNDIT-hd devices with 6.7% power conversion efficiency and 73% external quantum efficiency. The improved photovoltaic properties of the selenophene-containing acceptor copolymer relative to the thiophene counterpart originate from enhanced light harvesting, more favorable molecular packing in blends, and reduced charge recombination losses in devices. These findings demonstrate that selenophene substitution for thiophene in donor− acceptor copolymers is an effective strategy that enhances the intrinsic polymer properties as well as the performance of all-polymer solar cells incorporating them.

N-Type Doping of Naphthalenediimide-Based Random Donor–Acceptor Copolymers to Enhance Transistor Performance and Structural Crystallinity

“…This is because the electron affinity of selenium is stronger than that of sulfur, which potentially favors the intrachain charge transfer on the backbone. 49 In addition, the larger size of selenium than sulfur facilitates soothing the space between the highly rigid acceptor moieties to promote chain packing. 50 For the monomers employed, M1, NN, and NDI-SiC8 were synthesized according to the methods reported in the literature, except for S, N, and SS.…”

“…Also, we used a selenophene spacer ( M1 ) instead of the conventional thiophene spacer in the random polymerization process. This is because the electron affinity of selenium is stronger than that of sulfur, which potentially favors the intrachain charge transfer on the backbone . In addition, the larger size of selenium than sulfur facilitates soothing the space between the highly rigid acceptor moieties to promote chain packing .…”

18.1% Ternary All‐Polymer Solar Cells Sequentially Processed from Hydrocarbon Solvent with Enhanced Stability

“…To avoid the use of CF, effort has been spent on solvents with high boiling points such as chlorobenzene xylene. [ 25,26 ] As shown in Figure 1 (red region), typically, these solvents, particularly non‐halogen solvents, cannot afford PCEs as high as CF. [ 27 ] Most of the time, the eco‐friendlier hydrocarbon solvents lead to PCEs significantly lower than CF, because the physical chemistry among donor‐acceptor‐solvent, for example, their phase diagram and the drying kinetics of the solution, are essentially different from fast‐drying solvents such as CF.…”

Conductive Polymers for Flexible and Stretchable Organic Optoelectronic Applications

“…Over the past two decades, organic optoelectronics on solid substrates have received great developments, − for example, single-junction organic solar cells (OSCs) have recently gained great signs of progress with the efficiencies over 19% . Nevertheless, devices on rigid surfaces could not match with irregular surfaces or the products needed to be stretched.…”