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Abstract
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Poly(3-thiophene ethanol) (P3ThEt)-g-polystyrene (PSt) and P3ThEt-g-polyaniline (PANI) bottlebrushes were
used as morphology compatibilizers in poly[benzodithiophene-bis(decyltetradecyl-thien) naphthothiadiazole]
(PBDT-DTNT):phenyl-C61-butyric acid methyl ester (PC61BM) and poly[bis(triiso-propylsilylethynyl) benzodithiophene-bis(decyltetradecyl-thien) naphthobisthiadiazole] (PBDT-TIPS-DTNT-DT):PC61BM photovoltaics.
Although 10 wt% of P3ThEt-g-PSt and P3ThEt-g-PANI bottlebrushes improved the cell features (4.39–4.42%
versus 3.24%), a 20 wt% was found to be the optimal compatibilizer content and performances of 5.34 and
5.26% were detected, respectively. Polythiophenic backbones covered with either coily PSt brushes or rod PANI
brushes enabled the simultaneous growth of donor and acceptor assemblies in these systems. Therefore, the hole
(4.6 × 10−3 and 4.9 × 10−3 cm2/V·s) and electron (5.1 × 10−2 and 5.5 × 10−2 cm2/V·s) mobilities and also
other photovoltaic properties (12.68 and 12.71 mA/cm2; 61 and 60%; 0.69 and 0.69 V) were improved. In
contrast, PBDT-TIPS-DTNT-DT based devices did not beneft from bottlebrush compatibilizers as much as PBDTDTNT based ones and performance peaked at 3.81% for PBDT-TIPS-DTNT-DT:PC61BM:10 wt% P3ThEt-g-PSt
system. Herein, addition of rod-coil and rod-rod bottlebrushes further affected PC61BM clustering than polymer
crystallization with complicated structures and TIPS side groups. Only 10 wt% of bottlebrushes, especially rodcoil P3ThEt-g-PSt ones, was enough in regulating the PCBM molecules and enhancing cell parameters.
Thereafter, further raising the compatibilizer population saturated the active layer and, consequently, device
functions especially hole mobility plummeted. The smallest charge transfer resistances (Rtr) also belonged to
PBDT-DTNT:PC61BM:20 wt% P3ThEt-g-PSt (=273 Ω·cm2) and PBDT-DTNT:PC61BM:20 wt% P3ThEt-g-PANI
(=276 Ω·cm2). In optimum PBDT-DTNT:PC61BM and PBDT-TIPS-DTNT-DT:PC61BM systems, the recombination
time values r
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