Thieno[3,2‐b]thiophene‐diketopyrrolopyrrole Containing Polymers for Inverted Solar Cells Devices with High Short Circuit Currents

Abstract

The synthesis and characterization four diketopyrrolopyrrole containing conjugated polymers for use in organic photovoltaics is presented. Excellent energy level control is demonstrated through heteroatomic substitution whilst maintaining similar solid state properties as shown by X-ray diffraction and atomic force microscopy. Inverted solar cells were fabricated with the best devices having short circuit currents exceeding 16 mA cm − 2 and effi ciencies of over 5% irrespective of whether [6,6]-phenyl-C 61 -butyric acid methyl ester (PC 60 BM) or [6,6]-phenyl-C 71 -butyric acid methyl ester (PC 70 BM) is used. Transient absorption spectroscopy on the bulk heterojunction blends shows effi cient charge photo-generation, with the variations in short circuit current correlated to the energetic offset between polymer and fullerene.

Pyrrolo[2,3-d:5,4-d′]bisthiazoles: Alternate Synthetic Routes and a Comparative Study to Analogous Fused-Ring Bithiophenes

“…Typical values for N -alkylDTPs are 25 000–30 000 M –1 cm –1 , while the analogous 4-alkylPBTz values given in Table are only 14 000–16 000 M –1 cm –1 . This trend in reduced absorptivity has been previously reported for other cases in which thiophene has been replaced by thiazole, − and computational studies have shown that the transition oscillator strength continues to decrease with each additional substitution by thiazole . Even the parent heterocycles themselves exhibit this difference in absorptivity.…”

Influence of Chemical Structure on the Charge Transfer State Spectrum of a Polymer:Fullerene Complex

“…As such, charge separation is likely to be difficult for this system. It should be noted, however, that when PC 71 BM aligns with DPP, we calculate a state with almost complete charge transfer only 0.01 eV higher in energy (thermally accessible at room temperature), which is consistent with the limited degree of charge generation reported for PDPP-TT-Tz:PC 71 BM …”

Thiophene‐Extended Nickel Thiazoledithiolene: π‐Extended Fused‐Ring Metal Dithiolenes with Stabilized Frontier Orbitals

“…Decreased molar absorptivity as the result of substituting thiophene with thiazole has been previously noted by other authors,, and computational studies have shown that the transition oscillator strength continues to decrease with each additional substitution by thiazole . This difference in absorptivity can also be seen in the parent heterocycles themselves.…”