328
S. Peiris et al.
could affect performance. They serendipitously found that the solvent system used
to dissolve the dye could greatly influence cell performance. As a result of applying
acetonitrile/THF solvent system in 1:1 ratio, the dye zzx-op1-2 outperformed the
other two dyes (zzx-op1 and zzx-op1-3; Fig. 16.11) giving a photocurrent density of
7.57 mA cm
−2 under full sun illumination (simulated AM 1.5G light illumination,
100 mW cm
−2 , V OC = 117 mV, FF = 0.4, η = 0.353%). It is exciting that these cells
with zzx-op1-2 dye, have excellent long-term stability. Moreover, it was found that
this particular dye has comparatively longer hole lifetime, lower photocurrent losses
and higher photogenerated hole density (Liu et al. 2014a).
Two novel donor–π acceptor push-pull dyes based on organometallic ruthenium
di acetylide complexes, which could be applied for p-DSCs, were reported on by Lyu
et al. Though these dyes are still not optimized, it is observed that their photovoltaic
performance is relatively high compared to other ruthenium polypyridine complexes
(J SC = 2.25 mA cm
−2 , V OC = 104 mV, FF = 0.34, η = 0.79%). According to the
investigators lowering the energy level the HOMO will yield ruthenium diacetylide
dyes with high performances due to enhancing injection Gibbs free enthalpy (Lyu
et al. 2016).
Vasilis Nikolaou et al. synthesised the first covalently linked zinc porphyrinfullerene (ZnP-C60) Donor-Acceptor dyads that can be used in p-DSCs. Three such
structures (C60ZnPCOOH, C60-trZnPCOOH and C60trZnPtrCOOH) were synthesised and used as sensitizers in NiO-DSCs. Ultrafast transient absorption spectroscopy illustrates that there is a long-lived charge separation achieved with the
shift of electrons from the porphyrin core (reduced) to the C60. Further, the transient experiments show that triazole ring also could expand the lifetime of charge
separated state. In addition, they have examined the effect of introducing a spacer
group with different lengths in between the electron acceptor and porphyrin macrocycle in order to reduce the charge recombination. The photo conversion efficiency
of the best performing dyad with I 3
− /I
− electrolyte is 0.076% (V OC = 109 mV; J SC
= 1.86 mA cm
−2 ; FF = 0.35) (Georgios Coutsolelos et al. 2018).
A zinc-porphyrin sensitizer has been also been designed by Jianfeng Lu et al.
They have developed a D-π-A system by connecting the electron donor-di(pcarboxyphenyl)amine (DCPA) and the electron acceptor- perylenemonoimide (PMI)
through a zinc(II) porphyrin having alkyl chains which act as a π- conjugated
bridge. When the dye is fabricated into a p-DSC, with NiO semiconductor and
tris(acetylacetonato) iron(III/II) redox mediator a power conversion efficiency of
0.92% has been observed under simulated 100 mW cm
−2 (AM 1.5G irradiation) (Lu
et al. 2018).
Hanni Wu et al. have developed Zn porphyrin-polyoxometalate hybrids incorporating different p-linkers which can be utilized as sensitizers in p-DSCs. They have
made use of density functional theory method and time dependant density functional
theory method to investigate the impact created on sensitizers by the p-linkers and
have observed higher delocalization with longer p-linkers (Wu et al. 2016).
The groups of Koten (He et al. 2014) and Grätzel (Bessho et al. 2009) separately
used cyclometalated Ru(II) complexes in n-DSCs. A significant recognition is given
to these complexes due to their electrochemical and photochemical stability, and
S. Peiris et al.
could affect performance. They serendipitously found that the solvent system used
to dissolve the dye could greatly influence cell performance. As a result of applying
acetonitrile/THF solvent system in 1:1 ratio, the dye zzx-op1-2 outperformed the
other two dyes (zzx-op1 and zzx-op1-3; Fig. 16.11) giving a photocurrent density of
7.57 mA cm
−2 under full sun illumination (simulated AM 1.5G light illumination,
100 mW cm
−2 , V OC = 117 mV, FF = 0.4, η = 0.353%). It is exciting that these cells
with zzx-op1-2 dye, have excellent long-term stability. Moreover, it was found that
this particular dye has comparatively longer hole lifetime, lower photocurrent losses
and higher photogenerated hole density (Liu et al. 2014a).
Two novel donor–π acceptor push-pull dyes based on organometallic ruthenium
di acetylide complexes, which could be applied for p-DSCs, were reported on by Lyu
et al. Though these dyes are still not optimized, it is observed that their photovoltaic
performance is relatively high compared to other ruthenium polypyridine complexes
(J SC = 2.25 mA cm
−2 , V OC = 104 mV, FF = 0.34, η = 0.79%). According to the
investigators lowering the energy level the HOMO will yield ruthenium diacetylide
dyes with high performances due to enhancing injection Gibbs free enthalpy (Lyu
et al. 2016).
Vasilis Nikolaou et al. synthesised the first covalently linked zinc porphyrinfullerene (ZnP-C60) Donor-Acceptor dyads that can be used in p-DSCs. Three such
structures (C60ZnPCOOH, C60-trZnPCOOH and C60trZnPtrCOOH) were synthesised and used as sensitizers in NiO-DSCs. Ultrafast transient absorption spectroscopy illustrates that there is a long-lived charge separation achieved with the
shift of electrons from the porphyrin core (reduced) to the C60. Further, the transient experiments show that triazole ring also could expand the lifetime of charge
separated state. In addition, they have examined the effect of introducing a spacer
group with different lengths in between the electron acceptor and porphyrin macrocycle in order to reduce the charge recombination. The photo conversion efficiency
of the best performing dyad with I 3
− /I
− electrolyte is 0.076% (V OC = 109 mV; J SC
= 1.86 mA cm
−2 ; FF = 0.35) (Georgios Coutsolelos et al. 2018).
A zinc-porphyrin sensitizer has been also been designed by Jianfeng Lu et al.
They have developed a D-π-A system by connecting the electron donor-di(pcarboxyphenyl)amine (DCPA) and the electron acceptor- perylenemonoimide (PMI)
through a zinc(II) porphyrin having alkyl chains which act as a π- conjugated
bridge. When the dye is fabricated into a p-DSC, with NiO semiconductor and
tris(acetylacetonato) iron(III/II) redox mediator a power conversion efficiency of
0.92% has been observed under simulated 100 mW cm
−2 (AM 1.5G irradiation) (Lu
et al. 2018).
Hanni Wu et al. have developed Zn porphyrin-polyoxometalate hybrids incorporating different p-linkers which can be utilized as sensitizers in p-DSCs. They have
made use of density functional theory method and time dependant density functional
theory method to investigate the impact created on sensitizers by the p-linkers and
have observed higher delocalization with longer p-linkers (Wu et al. 2016).
The groups of Koten (He et al. 2014) and Grätzel (Bessho et al. 2009) separately
used cyclometalated Ru(II) complexes in n-DSCs. A significant recognition is given
to these complexes due to their electrochemical and photochemical stability, and