The role of the pi-bridge length in the performance of diketopyrrolopyrrole-based organic dyes for dye-sensitized solar cells

• Three novel diketopyrrolopyrrole-based metal-free organic dyes (TPh, BPh and SPh) with different pi-bridge lengths were designed and synthesized for dye-sensitized solar cells (DSSCs). The phenyl units were employed as the additional pi-bridge for the three dyes, which located between the diketopyrrolopyrrole core and cyanoacrylic acid unit. Interestingly, it is the first time to report a diketopyrrolopyrmle-based dye with only one additional pi-bridge unit (SPh). The effects of pi-bridge length on photophysical, molecular planarity, energy level and photovoltaic properties of the dyes were systematically investigated. The results revealed that the prolongation of pi-bridge length by introducing an additional phenyl unit results in an extra torsion in the structural framework and reduces the molecule planarity, which has a negative impact on improving the light-harvesting ability, while it is beneficial in lowering the tendency of aggregation and enhancing the excited electron injection efficiency. Finally, with a moderate pi-bridge length (BPh), the best balance of overall performances is achieved, resulting in the highest power conversion efficiency (6.57%) without chenodeoxycholic acid.

Ämnesord

NATURVETENSKAP  -- Kemi -- Fysikalisk kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences -- Physical Chemistry (hsv//eng)

NATURVETENSKAP  -- Kemi -- Materialkemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences -- Materials Chemistry (hsv//eng)

Nyckelord

Dye-sensitized solar cells

Metal-free organic dye

Diketopyrrolopyrrole

Triphenylamine

pi-bridge length

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