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Four new donor–acceptor conjugated polymers based on the acceptor block 8,10-bis(2-octyldodecyl)-8H-dithieno[3′,2′:5,6;2′′,3′′:7,8]naphtho[2,3-d]imidazole-9(10H)-one and various donor moieties were synthesized. Binary and ternary composites comprising new polymers, PC71BM fullerene and non-fullerene acceptors based on indacenodithiophene, were developed. The mobility of electrons and holes in thin films of the ternary composites is balanced in contrast to that in binary composite films. This is explained by less aggregation in the ternary composite films and good matching of the frontier orbital energy levels of the composite components. [ABSTRACT FROM AUTHOR]

A [3 + 2] cycloaddition reaction using dialkyne and diazide comonomers, both bearing explosophoric groups, to synthesize energetic polymers containing furazan and 1,2,3-triazole ring as well as nitramine group in the polymer chain have been described. The developed solvent- and catalyst-free approach is methodologically simple and effective, the comonomers used are easily available, and the resulting polymer does not need any purification. All this makes it a promising tool for the synthesis of energetic polymers. The protocol was utilized to generate multigram quantities of the target polymer, which has been comprehensively investigated. The resulting polymer was fully characterized by spectral and physico-chemical methods. Compatibility with energetic plasticizers, thermochemical characteristics, and combustion features indicate the prospects of this polymer as a binder base for energetic materials. The polymer of this study surpasses the benchmark energetic polymer, nitrocellulose (NC), in a number of properties. [ABSTRACT FROM AUTHOR]

Two donor–acceptor (D–A) backbone copolymers with different fused ring acceptors, i.e., dithieno [2,3‐e:3′,2′‐g]isoindole‐7,9(8 H)‐dione (DTID) and dithieno[3′,2′:5,6;2″,3″:7,8]naphtho[2,3‐d]imidazol‐9(10 H)‐one (DTNID) and same benzo[1,2‐b:4,5‐b′]dithiophene with alkylated aromatic side as side chains (BDTT) donor, denoted as P133 and P135 are synthesized and used as donor along with narrow bandgap nonfullerene Y6 acceptor for the preparation of polymer solar cells (PSCs). The dielectric constant of P135:Y6 is higher than that of P133:Y6 due to the strong electron deficient ability of DTNID compared to DTID, which fostered exciton dissociation and charge transport, constrained charge recombination, and ultimately boosted the power conversion efficiency of P135:Y6 to 15.11%, which is higher than P133:Y6 (10.24%). Therefore, these investigations confirm the pronounced potential of fused ring DTNID as an acceptor unit for emerging D–A copolymers for PSCs with high efficiency. [ABSTRACT FROM AUTHOR]

A new acceptor unit anthra[1,2‐b: 4,3‐b': 6,7‐c'']trithiophene‐8,12‐dione (А3Т) (A2) is synthesized and used to design D‐A1‐D‐A2 medium bandgap donor copolymers with same thiophene (D) and A2 units but different A1, i.e., fluorinated benzothiadiazole (F‐BTz) and benzothiadiazole (BTz) denoted as P130 and P131, respectively. Their detailed optical and electrochemical properties are examined. The copolymers show good solubility in common organic solvents, broad absorption in the visible spectral region from 300 to 700 nm, and deeper HOMO levels of −5.45 and −5.34 eV for P130 and P131, respectively. Finally, an optimized polymer solar cell (PSC) based on P131 as the donor and narrow bandgap non‐fullerene small molecule acceptor Y6 demonstrated a power conversion efficiency (PCE) of >11.13%. To further improve the efficiency of the non‐fullerene PSC, the P130 is optimized by introducing a fluorine atom into the BTz unit, F‐BTz acceptor unit, and PCE PSC based on P130: Y6 active layer increased to >15.28%, which is higher than that for the non‐fluorinated analog P131:Y6. The increase in the PCE for former PSC is attributed to the more crystalline nature and compact π–π stacking distance, leading to more balanced charge transport and reduced charge recombination. These remarkable results demonstrate that A3T‐based copolymer P130 with F‐BTz as the second acceptor is a promising donor material for high‐performance PSCs. [ABSTRACT FROM AUTHOR]

A simple synthesis of highly planar extended π‐electron molecules is of particular interest for the development of efficient nonfullerene acceptors in organic solar cells with high light absorption and high mobility. Herein, two small‐molecule acceptors (MPU7 and MPU8) with a diketopyrrolopyrrole core connected to CPTCN end‐capping groups (A2) via thienylethynylselenophene (MPU7) or thienylethynylthiophene (MPU8) linkers are conceived and synthesized. Planarity of the conjugated skeleton is achieved in both molecules, thanks to the existence of four (Se⋯O or S⋯O) noncovalent, through‐space intramolecular interactions. Both nonfullerene small‐molecule acceptors show broad absorption in the visible and near‐infrared region (up to 930 nm). As a result, the binary solar cells constructed together with a polymer donor (P) display power conversion efficiencies as high as 14.12%. Devices built with MPU7 (containing the selenophene) show better film morphology, electron mobility, and higher efficiency than those containing thiophene (MPU8). [ABSTRACT FROM AUTHOR]

A new wide‐bandgap conjugated D‐A polymer denoted as P106 with a medium acceptor dithieno [2,3‐e;3'2'‐g]isoindole‐7,9 (8H) (DTID) unit and strong 2‐dodecylbenzo[1,2‐b:3,4‐b':6,5‐b"]trithiophene (3TB) donor units shows an optical bandgap of 2.04 and highest occupied molecular orbital energy level of −5.56 eV. P106 is used as the donor and two nonfullerene acceptors‐medium bandgap DBTBT‐IC and narrow band Y18‐DMO‐are used as acceptors for the construction of binary and ternary bulk heterojunction polymer solar cells. The optimized polymer solar cells based on P106 : DBTBT‐IC and P106 : Y18‐DMO exhibit power conversion efficiencies of 11.76 % and 14.07 %, respectively. The short‐circuit current density (22.78 mA cm−2) for the P106 : Y18‐DMO device is higher than that for P106 : DBTBT‐IC (18.56 mA cm−2) one, which could be attributed to the more photon harvesting efficiency of the P106 : Y18‐DMO active layer. In light of the high short‐circuit current densities and fill factors for the Y18‐DMO based device and the high value of open circuit voltage of the DBTBT‐IC based device, ternary polymer solar cells are fabricated by using ternary active layer (P106 : DBTBT‐IC : Y18‐DMO) and achieve a power conversion efficiency of 16.49 % with low energy loss of 0.47 eV. [ABSTRACT FROM AUTHOR]

Herein, ternary active layer‐based polymer solar cells using two donor (D)–acceptor (A) conjugated polymers P1 and P3 having same A unit and different D units as donor along with the nonfullerene small molecule acceptor, BThIND‐Cl, are fabricated. The polymer solar cells based on P1:BThIND‐Cl and P3:BThIND‐Cl binary show power conversion efficiency of 12.13% and 13.08% with energy loss of 0.60 and 0.51 eV, respectively. The open circuit voltage of the P3 based polymer solar cells is higher than that for P1 counterpart associated with the deeper highest occupied molecular orbital (HOMO) energy level of P3 as compared to the P1. The small energy loss for P3 may be attributed to low HOMO offset between P3 and BThIND‐Cl. Moreover, the short circuit current density is higher for the P1 based polymer solar cell. Taking the advantages of high valve of short circuit current for P1 and larger value of open circuit voltage for P3 counterpart, optimized polymer solar cells using these two polymers and BThIND‐Cl as acceptor and after the optimization, the polymer solar cells based on P1:P3:BThIND‐Cl showed overall power conversion efficiency of 15.78% with energy loss of 0.55 eV. [ABSTRACT FROM AUTHOR]

The fast evolution of the narrow bandgap nonfullerene acceptors requires new conjugated wide bandgap polymers for the use of nonfullerene polymer solar cells (PSCs). Herein, two new wide bandgap A1–D1–A2–D1 conjugated polymers with the same dithieno[2,3‐e:3′,2′‐g]isoindole‐7,9(8H)‐dione (DTID) acceptor (A1) and thiophene donor (D1) and different A2 acceptor units, i.e., benzothiadiazole (BT) and fluorinated benzothiadiazole (f‐BT) denoted as P113 and P114, are designed, and the effect of fluorination of the BT acceptor unit on the photovoltaic properties of PSCs using nonfullerene acceptors is investigated. It is found that the incorporation of fluorine atom into the BT acceptor unit increases the absorption coefficients and the relative dielectric constant. The increase in photoluminescence quenching, reduction in charge recombination loss, and improvement in the charge carrier life are observed for P114. All these factors result in the drastically improved power conversion efficiency of P114:ITIC‐m‐based PSC to 10.42% with a small energy loss of 0.56 eV as compared with the P113 counterpart (8.74% with an energy loss of 0.69 eV) under identical conditions. The low energy loss is beneficial to overcome the trade‐off between open‐circuit voltage and short‐circuit current. [ABSTRACT FROM AUTHOR]

A series of novel donor–acceptor (D–A) random conjugated terpolymers P2‐P4 along with the homopolymers P1 (BDT‐DPP) and P5 (BDT‐BTDQ) were designed and synthesized by copolymerizing a benzo[1,2‐b:4,5‐b]dithiophene (BDT) donor with an electron‐deficient diketopyrrolo[3,4‐c]pyrrole (DPP) unit and a benzothiadiazolo[3,4‐e]quinoxaline (BTDQ) moieties of different electron‐withdrawing strengths, and the resultant terpolymers showed broad absorption profile ranging from 300 to 1200 nm. The HOMO levels of the polymers were adjusted from −5.23 to −5.11 eV, and the optical bandgaps were controlled from 1.32 to 1.13 eV by changing the molar ratio of DPP and BTDQ acceptors. These terpolymers were used as a donor along with PC71BM as an acceptor for the creation of polymer solar cells, and the performance was optimized via variable the donor to acceptor ratio and solvent vapor annealing. The polymer solar cells made from the random terpolymer P3 showed the highest overall power conversion efficiency of (9.27%), which is higher than that for the corresponding homo‐polymers counterparts, that is, P1 (7.27%) and P5 (7.68%). The results demonstrate that the designing of random D‐A1‐D‐A2 terpolymers may be the best approach for efficient polymer solar cells. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1478–1485 [ABSTRACT FROM AUTHOR]

ABSTRACT Two copolymers having D-A-D-A ( P1) and D-A ( P2) structures with quinoxaline acceptor unit and dithienosilole donor unit were synthesized and their optical and electrochemical (both experimental and theoretical) properties were investigated. The optical properties showed that these copolymers P1 and P2 exhibit optical bandgaps of 1.54 and 1.62 eV, respectively, with broader absorption profiles extending up to 800 nm and 770 nm, respectively. The electrochemical investigation of these two copolymers indicates that they exhibit suitable highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels for efficient exciton dissociation and high open circuit voltage in the resultant polymer solar cells (PSCs). These copolymers were used as donors along with the PC71BM as acceptor for the fabrication of solution processed bulk heterojunction PSCs. The optimized P1:PC71BM and P2:PC71BM active layers treated with solvent vapor treatment showed overall power conversion efficiency (PCE) of 7.16% and 6.57%, respectively. The higher PCE of P1-based device as compared to P2 might be attributed to higher crystallinity of P1 and good hole mobility resulting more balanced charge transport. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 376-386 [ABSTRACT FROM AUTHOR]

A new non-fullerene small molecule acceptor, MPU2, that incorporates dicyano-rhodanine moieties on the edges of thiophene–diketopyrrolopyrrole was designed and prepared. In films MPU2 showed a broad absorption in the 550–850 nm region with an optical energy gap of 1.59 eV. MPU1 and MPU2 were used as small molecule acceptors to construct solar cells. DTS(QxHTh2)2, which has a D1–A–D2–A–D1 structure and complementary absorption in the 470–700 nm region of the solar spectrum, was selected as the electron-donor. All small molecule solution-processed bulk heterojunction organic solar cells were prepared using these small molecules as acceptors along with a small molecule donor. In these devices, MPU2 showed higher power conversion efficiency than MPU1. The morphology of the active layer was improved by applying thermal annealing and vacuum drying methodologies. The devices for which the latter methodology was used showed 6.28% (MPU1) and 7.76% (MPU2) power conversion efficiencies (PCEs), with the latter value being one of the highest PCEs for all small molecule fullerene-free solar cells. The results of this study show that vacuum drying treatment of the active layer is better than thermal annealing to achieve high PCE values. [ABSTRACT FROM AUTHOR]