Improved photovoltaic performance of two-dimensional low band-gap conjugated polymers with thieno[3,2-b]thiophene and diketopyrrolopyrrole units by altering pendent position of conjugated side chain

A‐D‐A Type Small Molecules Based on Boron Dipyrromethene for Solution‐Processed Organic Solar Cells

“…We fabricated photovoltaic devices with the following layer structure:I TO/PEDOT:PSS/active layer/PFN/Al( ITO:i ndium tin oxide, PEDOT:PSS:p oly (3,4-ethylenedioxythiophene): poly(styrene sulfonate), PFN:p oly [(9,9-bis(30-(N,N-dimethylamino)propyl)-2,7-fluorene)]-alt-2,7-(9,9-dioctylfluorene), in whichB DTT-BODIPY,F L-BODIPY or TT-BODIPY was used as the donor material andP C 61 BM or PC 71 BM as the acceptor material. With careful optimization of the processing parameters such as the acceptor material, the ratio of donor to acceptor (w/w), the thickness of active layer,a nd the volumeo fa dditives ( Figures S5-S7, Ta bles S1-S2, SupportingI nformation), [16] their best performances were achieved with a1:1.5 ratio of donor to PC 71 BM acceptora nd the thicknesses of 80, 75, and 50 nm obtained from an CB solution at at otal solid concentration of 25 mg mL À1 under as pin-coating rate of 1400, 1600, and 1800 rpm for BDTT-BODIPY,F L-BODIPY,a nd TT-BODIPY,r espectively,i nt he presence of 0.4 %1 ,8-diiodooctane (DIO) additive. Figure 3s hows the J-V curveso ft he optimized OSCs under illumination of AM 1.5 solar irradiance (100 mW cm À2 ), and the corresponding photovoltaic data are summarized in Table 2.…”

Synthesis of di(ethylene glycol)-functionalized diketopyrrolopyrrole derivative-based side chain-conjugated polymers for bulk heterojunction solar cells

“…The second absorption band, in the range 550-900 nm, originated from intramolecular charge transfer (ICT) between the thiophene-based donor units and DG-TDPP-based acceptor units. 33,34 The absorption intensities of the second absorption band increased upon increasing the content of DG-TDPP units in the copolymers, both in solution and as thin lms. Moreover, the red-shis and full widths at half-maximum of the absorption bands of the copolymers in their lm forms were greater than those in solution, presumably because of strong noncovalent interactions (e.g., p-stacking) between the polymer backbones and conjugated pendant units.…”

“…[28][29][30][31][32] The presence of TDPP units in the polymer backbone enhanced the absorption edge to wavelengths of up to 1000 nm. [33][34][35] Unfortunately, increasing the TDPP content decreased the solubility of the polymers, due to increased degrees of p-p stacking among the polymer chains. The power conversion efficiencies (PCEs) of such polymer-based PSCs are not high.…”

“…The power conversion efficiencies (PCEs) of such polymer-based PSCs are not high. 33,34 Therefore, precise control over the molar ratio of electron-donating and -withdrawing units in a polymer chain is necessary to optimize the solubility and the optical and PV performance of their devices.…”

Enhanced photovoltaic properties of di(dodecylthiophene)-alt-2,3-di(3-octoxylphenyl)-5,8-dithieno[3,2-b]thiophene 6,7-difluoroquinoxaline copolymer by fluorination

“…The SCLC can be approximated according to MotteGurney equation J ¼ (9/8)ε 0 ε r m(V/d 3 ), in which J is the current density, ε r is the dielectric constant of the polymer, ε 0 is the free-space permittivity (8.85 Â 10 À12 F/m), d is the thickness of the blended film layer (60 nm and 80 nm for PBT-TTQ-H and PBT-TTQ-F, respectively), V ¼ V appl À V bi , V appl is the applied potential, and V bi is the built-in potential which results from the difference in the work function of the anode and the cathode [22]. After cooled down to room temperature, the mixture was poured into methanol (100 mL) and precipitation was occurred.…”