A Review on Contemporary Hole Transport Materials …
147
Fig. 1 Structure of
Spiro-OMeTAD
and poor conductivity (~10
−5 ) in its original form. To counter this, it is usually
blended with certain additives like TBP (4-tert-butylpyridine) and Li-TFSI (lithium
bis(trifluoromethylsulfonyl)) to increase the conductivity for hole transport and collection and decrease recombination at the interface (Snaith and Grätzel 2006). But
it is found that additives may lead to decrease in the long-term stability of the spiro
structure.
Snaith and his co-workers used a low-cost method to develop a mesostructured
PSC with an efficiency of 10.9% (Lee et al. 2012). This was done using mesoporous
alumina scaffold, a mixed halide perovskite absorber, and Spiro-OMeTAD. Then, a
sequential deposition method was proposed by Julian and Graetzel (2013) to deposit
perovskite pigment to the porous metal oxide using Spiro-OMeTAD as a HTM
(Fig. 2). A power conversion efficiency of about 15% was achieved using his method.
Spiro-OMeTAD has also been doped with p-type dopants like Li and Co to
achieve an efficiency as high as 19.7% (Li et al. 2016; Kumari et al. 2019). Nam
and Co-workers found out that just by changing the position of methoxy groups in a
Fig. 2 Cross-sectional SEM image of a photovoltaic perovskite cell using Spiro-OMeTAD.
Reprinted with permission from Burschka (2013) Copyright (2013) Nature
147
Fig. 1 Structure of
Spiro-OMeTAD
and poor conductivity (~10
−5 ) in its original form. To counter this, it is usually
blended with certain additives like TBP (4-tert-butylpyridine) and Li-TFSI (lithium
bis(trifluoromethylsulfonyl)) to increase the conductivity for hole transport and collection and decrease recombination at the interface (Snaith and Grätzel 2006). But
it is found that additives may lead to decrease in the long-term stability of the spiro
structure.
Snaith and his co-workers used a low-cost method to develop a mesostructured
PSC with an efficiency of 10.9% (Lee et al. 2012). This was done using mesoporous
alumina scaffold, a mixed halide perovskite absorber, and Spiro-OMeTAD. Then, a
sequential deposition method was proposed by Julian and Graetzel (2013) to deposit
perovskite pigment to the porous metal oxide using Spiro-OMeTAD as a HTM
(Fig. 2). A power conversion efficiency of about 15% was achieved using his method.
Spiro-OMeTAD has also been doped with p-type dopants like Li and Co to
achieve an efficiency as high as 19.7% (Li et al. 2016; Kumari et al. 2019). Nam
and Co-workers found out that just by changing the position of methoxy groups in a
Fig. 2 Cross-sectional SEM image of a photovoltaic perovskite cell using Spiro-OMeTAD.
Reprinted with permission from Burschka (2013) Copyright (2013) Nature