Abstract
The effect of co-absorbance on the performance of DSSC devices with a new design of dimer sensitizers possessing a 2,5-dihydropyrrolo[3,4-
c
]pyrrole-1,4-dione (DPP) bridge and various donor groups (carbazole, diphenyl amine, indole) is reported in the present work. The co-absorbent (CDCA = chenodeoxycholic acid) was inserted into the sensitizers and the photovoltaic performance was studied. The co-absorbent had a significant effect on
J
sc
,
V
oc
and the efficiency. Without incorporation of the co-absorbent, a higher efficiency of around 4.40% is exhibited (
J
sc
= 9.91 mA cm
−2
and
V
oc
= 0.678 V) by the R3 device, while after adding the co-absorbent, we have achieved an efficiency of around 4.44% (
J
sc
= 10.3 mA cm
−2
and
V
oc
= 0.693 V). Structure optimization and energy level calculations were carried out by density functional theory (DFT) with different donor substituents and DPP bridge based sensitizers. The co-absorbent and sensitizer based DSSCs were also characterised by impedance spectroscopy and incident photon to current conversion efficiency measurements.