Mini Review
Open Access
Review of Recent Progress of Perovskite Solar Cells
Without Spiro-OMeTAD
Vijaya Shankar, Teresa Demeritte and Qilin Dai*
Department of Physics, Atmospheric Sciences and Geoscience, Jackson State University, Jackson, Mississippi, USA
*Corresponding author: Department of Physics, Atmospheric Sciences and Geoscience, Jackson State University, Jackson, Mississippi 39217, USA, Email:
@
Received: September 28, 2016; Accepted: September 29, 2016; Published: October 04, 2016
Citation: Shankar V, Demeritte T, Dai Q (2016) Review of Recent Progress of Perovskite Solar Cells Without Spiro-OMeTAD. Nanosci
Technol 3(1): 1-2. DOI: http://dx.doi.org/10.15226/2374-8141/3/1/00136
Author NoteTop
The Power Conversion Efficiency (PCE) of Perovskite Solar Cells
(PSCs) has been boosted to over 20%. However, it is still challenging
to extend the PSCs to outdoor applications, such as the cost and the
stability of the devices. The reported PSCs with high PCE are all
based on Spiro-OMeTAD, which is a very expensive material. Spiro-
OMeTAD as whole transporting material (HTM) protects perovskite
material from degradation. The poor stability of the PSCs also can
be improved by a better HTM. Some researchers are investigating
new type of HTMs with an emphasis on excellent charge transfer
efficiency and high stability. This review summarizes recent studies
of the progress of PSC device performance with new type of HTM,
instead of Spiro-OMeTAD.
Introduction
PSCs have been studied extensively recently due to their
high record (over 20%) within four years due to the excellent
photoelectrical properties of perovskite material [1]. The high
PCE may meet the requirement of outdoor applications, which is
comparable to silicon solar cells. However, it is still challenging
to utilize PSCs for practical application based on the current
research due to their poor stability and cost issues. The poor
stability is caused by the perovskite material sensitive to the
moisture and the high cost is due to the Spiro-OMeTAD and other
materials. All the reports about high PCE of PSCs are based on
Spiro-OMeTAD as HTM, and it is reported that the protection
of Spiro-OMeTAD to perovskite material is not very well due to
the pin-holes in Spiro-OMeTAD layer leading to the moisture
penetration into the devices and degradation of the devices. The
preparation of Spiro-OMeTAD layer is reported to be spin coating
which is related with the uniform film and unavoidable pin-holes
[2]. The deposition method with the ability of preparing uniform
thin films is not suitable to be applied to Spiro-OMeTAD due
to the low decomposition temperature of the organic material.
Therefore, the Spiro-OMeTAD is associated with stability and the
cost of PSCs, and the investigation of other HTM is very critical
to the development of PSCs. Some researchers explore some new type of PSCs without Spiro-OMeTAD. In this mini review,
we summary the recent progress about the PSCs without Spiro-
OMeTAD including the PCE, stability and the device engineering.
Discussion
[5] Reported a PSC structure without a whole conductor in
their devices, and a PCE of12.8% was obtained in their study [3].
The perovskite solar cell is constructed by using the mesoporous
layers of TiO2 and ZrO2 which are deposited on FTO covered
glass substrate, and the cell structure does not require a hole
conducting layer. The stability of this type of PSCs is more than
1000 h in ambient air under full sunlight. This is the first report
about the PSC stability under full sunlight. The big achievement
is attributed to the ZrO2 since the devices without ZrO2 structure
were also investigated in their work. ZrO2 can block the flow
of photo generated electrons to the back contact preventing
recombination with the holes from the perovskite at the back
contact leading to high PCE. Figure 2B shows another type of
PSCs without Spiro-OMeTAD. In this structure, PEDOT: PSS was
used as HTM; PCBM extracts electrons from perovskite solar
cells. This structure is derived from organic solar cells, which
usually have poor stability. However, recently [4] reported a
PCE of 12.52% with this structure and optimized the stability by
two-dimensional ruddles den-popper structure (Figure 2B) [4].
The stability was increased to 2250 h under constant, standard
illumination. [5] Tried several of HTMs by the traditional PSC
structure, where TiO2 was used as electron transport layer [5]. Table 1C shows the photovoltaic performance of PSCs based
on different HTMs [5]. It can be seen that the efficiency of TTF
based devices is compared with that of Spiro-OMeTAD, while
P3HT based PSCs is not as good as Spiro-OMeTAD. The efficiency
of TTF based PSCs decreased to 9% from 10% under ambient
atmosphere, compared to 1% for Spiro-OMeTAD based devices.
Conclusion
We reviewed the research progress of PSCs without Spiro-
OMeTAD. The stability is much better than that of Spiro-OMeTAD
Figure 1:A Schematic drawing of a hole-conductor-free PSC. From [A.
Mei, X. Li, L. Liu, Z. ku, T. Liu, Y. Rong, M. Xu, M. Hu, J. Chen, Y. Yang, M.
Gratzel and H. Han, Science.2014, 345,295] Reprinted with permission
from AAAS. B another choice of the PSC without Spiro-OMeTAD and the
corresponding J-V curves for the planar devices without From [H. Tsai,
W. Nie, J. C. Blancon, C. C. Stoumpos, R. Asadpour, B. Harutyunyan, A. J.
Neukirch, R. Verduzco, J. J. Crochet, S. Tretiak, L. Pedesseau, J. Eren, M.
A. Alam, G. Gupta, J. Lou, P. M. Ajayan, M. J. Bedzyk, M. G. Kanatzidis and
A.D. Mohite. Nature 2016.313-316.] Reprinted with permission from
Nature Publishing Group under license number 3954941219208.C
photovoltaic performance of the PSCs based on different HTM. From
[J.Liu, Y.Wu, C.Qin, X.Yang, T.Yasudha, A.Islam, K.Zhang, W.Peng, W.Chen
and L.Han. 2014. Energy.Environ. Sci, 7,2963-2967.] Reprinted with
permission from Royal Society of Chemistry under license number
3957661474912.
but the efficiency of the current results is not that high as Spieo-
OMETAD. Therefore, we think more research effort will be
focused on improving the PCE and keep the current long term
stability.
Acknowledgements
This work was supported by National Science Foundation
under award #1332444.
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