A Soluble High Molecular Weight Copolymer of Benzo[1,2‐b:4,5‐b′]dithiophene and Benzoxadiazole for Efficient Organic Photovoltaics

Abstract

The synthesis and characterization of a soluble high molecular weight copolymer based on 4,8-bis(1-pentylhexyloxy)benzo[1,2-b:4,5-b']dithiophene and 2,1,3-benzoxadiazole is presented. High efficiency organic photovoltaic (OPV) devices comprised of this polymer and phenyl-C(71) -butyric acid methyl ester (PC(71) BM) were fabricated by additive processing with 1-chloronapthalene (CN). When the active layer is cast from pristine chlorobenzene (CB), power conversion efficiencies (PCEs) average 1.41%. Our best condition-using 2% chloronapthalene as a solvent additive in CB-results in an average PCE of 5.65%, with a champion efficiency of 6.05%.

Exploring Spray-Coating Techniques for Organic Solar Cell Applications

“…Initially, as a control, we fabricated devices using P3HT : PCBM as the absorbing layer and the performance was quit close to that reported elsewhere [10] and shown in Table 1 for the spray distance of 15 cm. A detailed study was then carried out for our P1 polymer [14] and based on this, the "intermediate zone" was found to be very similar to the P3HT system; around 15 cm, using the fixed solution made by dissolving 2.5 mg P1 and 5 mg PCBM in DCB. We note that the DCB solution will dry the film slower than chlorobenzene due to the higher boiling point and therefore gives us a wider window for film thickness control [15].…”

Donor–acceptor semiconducting polymers for organic solar cells

“…95 Coffin et al synthesized polymer 46c for which, due to the presence of the electronegative oxygen atom, a deeper HOMO was obtained when compared with 46a. 119 A preliminary PCE of 1.41% was obtained for BHJ with PC 71 BM. 119 A dramatic increase of PCE to 5.65% was observed upon the addition of 1-chloronaphthalene (2 wt %) as an additive.…”

“…119 A preliminary PCE of 1.41% was obtained for BHJ with PC 71 BM. 119 A dramatic increase of PCE to 5.65% was observed upon the addition of 1-chloronaphthalene (2 wt %) as an additive. 119 Several groups have synthesized D-A copolymers by bridging the BDT and the benzothiadiazole acceptor through a conjugated moiety such as thiophene, alkylthiophene, and alkoxythiophene.…”

“…119 A dramatic increase of PCE to 5.65% was observed upon the addition of 1-chloronaphthalene (2 wt %) as an additive. 119 Several groups have synthesized D-A copolymers by bridging the BDT and the benzothiadiazole acceptor through a conjugated moiety such as thiophene, alkylthiophene, and alkoxythiophene. [111][112][113] A broadening of the absorption spectrum and improved hole mobility were observed for copolymers 47c-47i.…”

Absorption-enhanced polymer solar cells based on broad band-gap poly(triphenylamine-alt-benzo[c][1,2,5]selenadiazole) derivative

“…For D units, some versatile aromatic compounds are selected to construct the narrow band-gap polymers, for instance, fluorene [3], silafluorene [4], carbazole [5,6], indolo[3,2-b]carbazole [7,8], triphenylamine [9,10] and benzodithiophene [11][12][13], in which some of them display highly efficient photovoltaic performance through blending with fullerene derivatives as electron-accepting materials. In the part of A units, the electron-deficient moieties, such as benzothiadiazole [14], benzofurazan [15][16][17] and quinoxaline [18], are used widely due to their merits in feasible synthesis and functionalization. On the other hand, the benzo[c] [1,2,5]selenadiazole, an analog of benzothiadiazole, is attracted interest also in constructing red polymers for polymer lightemitting diodes (PLEDs) and D-A polymers for PSCs ascribing to its good electron-withdrawing ability and narrower band gap than benzothiadiazole [19].…”