A number of nanocrystalline, mesoporous large area (~0.2-2 cm 2 ) dye-sensitized solar cells (DSS... more A number of nanocrystalline, mesoporous large area (~0.2-2 cm 2 ) dye-sensitized solar cells (DSSCs) are probed by electrochemical impedance spectroscopy measurements to realize their carrier dynamics such as charge transport resistance (RCT), electron diffusion coefficient (Dη), and electron lifetime (τn) by applying an equivalent electrical model. The experimental upshots reveal that the electron lifetime relates with the device physical parameters which was neglected in previous studies. It is also found that the RCT relates negatively with the device area i.e. it decrease upon increasing photo-exposed area. The observed lowering of current density (JSC) over a series of experiments upon increasing the photoelectrode area is attributed to the decrease in RCT. The charge carriers upon injection into semiconductor layer find increased diffusion pathways and eventually recombine with the hole species when characterized by lower carrier lifetime. The thickness of the electrode film does not play an effective role indicating that the dynamics of larger area DSSCs differs largely from those of a single cell. The experimental results available indicate that a nearly complete collection of charge carriers is possible in large area modules provided the physical dimensions of photoelectrode area are considered. The results from the study hints future directions to build high efficiency DSSC modules and further asserts considering the diffusion length in twodimensions while fabricating larger area cells.
Photoanode plays a key role in dye sensitized solar cells (DSSCs) as a scaffold for dye molecules... more Photoanode plays a key role in dye sensitized solar cells (DSSCs) as a scaffold for dye molecules, transport medium for photogenerated electrons, and scatters light for improved absorption. Herein, tin oxide nanostructures unifying the above three characteristics were optimized by a hydrothermal process and used as photoanode in DSSCs. The optimized morphology is a combination of hollow porous nanoparticles of size ~50 nm and micron sized spheres with BET surface area (up to 29 m2/g) to allow large dye-loading and light scattering as well as high crystallinity to support efficient charge transport. The optimized morphology gave the highest photovoltaic conversion efficiency (~7.5%), so far achieved in DSSCs with high open circuit voltage (~700 mV) and short circuit current density (~21 mA/cm2) employing conventional N3 dye and iodide/triiodide electrolyte. The best performing device achieved an incident photon to current conversion efficiency of ~97%. The performance of the optimized tin oxide nanostructures was comparable to that of conventional titanium based DSSCs fabricated at similar conditions.
Tin oxide (SnO2) is a candidate for applications requiring high electrical conductivity and optic... more Tin oxide (SnO2) is a candidate for applications requiring high electrical conductivity and optical transparency such as photoanode in dye-sensitized solar cells (DSCs) due to its high electron mobility and wider optical transparency than many other metal oxide semiconductors (MOS). However, DSCs employing SnO2 show significantly lower photoconversion efficiency, due to its intrinsic limitation such as lower conduction band energy and iso electric point, compared to that achieved by popular choices such as TiO2. A survey of literature shows a revived interest in SnO2 based DSCs recently, for example, strategies to (i) increase the dye uptake, (ii) increase its Fermi energy level, and (iii) reduce the recombination such as increasing surface roughness and novel morphologies towards (i), and doping of transition metals for (ii) and (iii). In response to these investments, SnO2 based DSCs showed similar VOC and superior current than that achieved by TiO2. We have undertaken a critical review on the progress made in overcoming its limitations and capitalizing its advantages to fabricate more efficient DSCs and observe that more investment is required to reduce the recombination in SnO2 for it to be emerged as an efficiency record holder in DSCs.
Tin oxide (SnO2) is a candidate for applications requiring high electrical conductivity and optic... more Tin oxide (SnO2) is a candidate for applications requiring high electrical conductivity and optical transparency, such as a photoanode in dye-sensitised solar cells (DSSCs), due to its higher electron mobility and wider optical transparency than many other metal oxide semiconductors (MOS), such as TiO2 and ZnO. However, DSSCs employing SnO2 show significantly lower photoconversion efficiency, compared to that achieved by popular choices, such as TiO2, due to its intrinsic limitations such as lower conduction band energy and isoelectric point. A survey of literature shows a revived interest in SnO2- based DSSCs, for example, strategies to (i) increase the dye uptake, (ii) increase its Fermi energy level, and (iii) reduce the recombination, such as by increasing surface roughness and novel morphologies towards (i), and doping of transition metals for (ii) and (iii). In response to these improvements, SnO2-based DSSCs showed similar open circuit voltage and superior short circuit current to that achieved by TiO2. We have undertaken a critical review on the progress made in overcoming the limitations and capitalising the advantages of SnO2 to fabricate more efficient DSSCs.We identify that more investment is required to reduce the recombination in SnO2 for it to emerge as an efficiency record holder in DSSCs
Photoanode plays a key role in dye sensitized solar cells (DSSCs) as a scaffold for dye molecules... more Photoanode plays a key role in dye sensitized solar cells (DSSCs) as a scaffold for dye molecules, transport
medium for photogenerated electrons, and scatters light for improved absorption. Herein, tin oxide
nanostructures unifying the above three characteristics were optimized by a hydrothermal process and
used as photoanode in DSSCs. The optimized morphology is a combination of hollow porous nanoparticles
of size 50 nm and micron sized spheres with BET surface area (up to 29 m2/g) to allow large
dye-loading and light scattering as well as high crystallinity to support efficient charge transport. The
optimized morphology gave the highest photovoltaic conversion efficiency (7.5%), so far achieved in
DSSCs with high open circuit voltage (700 mV) and short circuit current density (21 mA/cm2) employing
conventional N3 dye and iodide/triiodide electrolyte. The best performing device achieved an incident
photon to current conversion efficiency of 90%. The performance of the optimized tin oxide nanostructures
was comparable to that of conventional titanium based DSSCs fabricated at similar conditions.
Working electrode (WE) fabrication offers significant challenges in terms of achieving higheffici... more Working electrode (WE) fabrication offers significant challenges in terms of achieving highefficiency dye-sensitized solar cells (DSCs). We have combined the beneficial effects of vertical nanorods grown on conducting glass substrate for charge transport and mesoporous particles for dye loading and have achieved a high photoconversion efficiency of (η) > 11% with an internal quantum efficiency of ∼93% in electrode films of thickness ∼7 ± 0.5 μm. Controlling the interface between the vertical nanorods and the mesoporous film is a crucial step in attaining high η. We identify three parameters, viz., large surface area of nanoparticles, increased light scattering of the nanorod–nanoparticle layer, and superior charge transport of nanorods, that simultaneously contribute to the improved photovoltaic performance of the WE developed.
A number of nanocrystalline, mesoporous large area (~0.2-2 cm 2 ) dye-sensitized solar cells (DSS... more A number of nanocrystalline, mesoporous large area (~0.2-2 cm 2 ) dye-sensitized solar cells (DSSCs) are probed by electrochemical impedance spectroscopy measurements to realize their carrier dynamics such as charge transport resistance (RCT), electron diffusion coefficient (Dη), and electron lifetime (τn) by applying an equivalent electrical model. The experimental upshots reveal that the electron lifetime relates with the device physical parameters which was neglected in previous studies. It is also found that the RCT relates negatively with the device area i.e. it decrease upon increasing photo-exposed area. The observed lowering of current density (JSC) over a series of experiments upon increasing the photoelectrode area is attributed to the decrease in RCT. The charge carriers upon injection into semiconductor layer find increased diffusion pathways and eventually recombine with the hole species when characterized by lower carrier lifetime. The thickness of the electrode film does not play an effective role indicating that the dynamics of larger area DSSCs differs largely from those of a single cell. The experimental results available indicate that a nearly complete collection of charge carriers is possible in large area modules provided the physical dimensions of photoelectrode area are considered. The results from the study hints future directions to build high efficiency DSSC modules and further asserts considering the diffusion length in twodimensions while fabricating larger area cells.
Various one-dimensional nano-morphologies, such as multiporous nanofibers (MPNFs), porous nanofib... more Various one-dimensional nano-morphologies, such as multiporous nanofibers (MPNFs), porous nanofibers
(PNFs), and nanowires (NWs) of SnO2, are synthesized using electrospinning technique by controlling the tin
precursor concentration. The MPNFs have 8-fold higher surface area compared to the other
morphologies. Dye-sensitized solar cells (DSCs) were fabricated using these nanostructures as
photoanodes and their performance was compared. The MPNFs surpass the performance of PNFs and
NWs as well as conventional TiO2 paste. Record photoconversion efficiency (PCE) of 7.4% was realized
in MPNFs DSCs, which was twice to that achieved using PNFs (3.5%). Furthermore, the MPNFs showed
over >80% incident photon to current conversion efficiency (22% higher than that achieved by spherical
P25 TiO2 particles) and also demonstrated 3 times longer electron lifetime and electron diffusion
length. Owing to the possibility to produce large quantities using electrospinning technique, huge
commercial potential of SnO2 nanostructures, and promising results achieved herein, the MPNFs are
expected soon to be utilized in commercial devices.
Rutile nanorods based perovskite solar cells Stability of perovskite solar cells Lifetime of solu... more Rutile nanorods based perovskite solar cells Stability of perovskite solar cells Lifetime of solution processed solar cells Rutile nanowires TiCl 4 treatment in perovskite solar cells a b s t r a c t High efficiency is routinely reported in CH 3 NH 3 PbI 3Àx Cl x sensitized mesoscopic solar cells (PSCs) employing planar and scaffold architectures; however, a systematic comparison of their photovoltaic performance under similar experimental conditions and their long term stability have so far not been discussed. In this paper, we compare the performance and durability of PSCs employing these two device configurations and conclude that although a planar architecture routinely provides high initial photoconversion efficiency (PCE), particularly high open-circuit voltage (V OC ), a scaffold is crucial to achieve long term durable performance of such devices. In a comparative study of scaffold (rutile nanorods, NRs) vs. planar devices, the efficiency in latter dropped off by one order of magnitude in~300 h despite their similar initial PCE of~12%. We compared the performance and the durability of two types of scaffolds, i.e., pristine and TiCl 4 treated NRs, and observed that the pristine NRs showed >10% improvement in the PCE after~1300 h whereas the cells employing post-treated NR scaffold retained~60% of initial value. We address the origin of the different photovoltaic performance of planar and scaffold devices in the context of photoanode morphology and its possible effect on the cell durability.
A number of nanocrystalline, mesoporous large area (~0.2-2 cm 2 ) dye-sensitized solar cells (DSS... more A number of nanocrystalline, mesoporous large area (~0.2-2 cm 2 ) dye-sensitized solar cells (DSSCs) are probed by electrochemical impedance spectroscopy measurements to realize their carrier dynamics such as charge transport resistance (RCT), electron diffusion coefficient (Dη), and electron lifetime (τn) by applying an equivalent electrical model. The experimental upshots reveal that the electron lifetime relates with the device physical parameters which was neglected in previous studies. It is also found that the RCT relates negatively with the device area i.e. it decrease upon increasing photo-exposed area. The observed lowering of current density (JSC) over a series of experiments upon increasing the photoelectrode area is attributed to the decrease in RCT. The charge carriers upon injection into semiconductor layer find increased diffusion pathways and eventually recombine with the hole species when characterized by lower carrier lifetime. The thickness of the electrode film does not play an effective role indicating that the dynamics of larger area DSSCs differs largely from those of a single cell. The experimental results available indicate that a nearly complete collection of charge carriers is possible in large area modules provided the physical dimensions of photoelectrode area are considered. The results from the study hints future directions to build high efficiency DSSC modules and further asserts considering the diffusion length in twodimensions while fabricating larger area cells.
Photoanode plays a key role in dye sensitized solar cells (DSSCs) as a scaffold for dye molecules... more Photoanode plays a key role in dye sensitized solar cells (DSSCs) as a scaffold for dye molecules, transport medium for photogenerated electrons, and scatters light for improved absorption. Herein, tin oxide nanostructures unifying the above three characteristics were optimized by a hydrothermal process and used as photoanode in DSSCs. The optimized morphology is a combination of hollow porous nanoparticles of size ~50 nm and micron sized spheres with BET surface area (up to 29 m2/g) to allow large dye-loading and light scattering as well as high crystallinity to support efficient charge transport. The optimized morphology gave the highest photovoltaic conversion efficiency (~7.5%), so far achieved in DSSCs with high open circuit voltage (~700 mV) and short circuit current density (~21 mA/cm2) employing conventional N3 dye and iodide/triiodide electrolyte. The best performing device achieved an incident photon to current conversion efficiency of ~97%. The performance of the optimized tin oxide nanostructures was comparable to that of conventional titanium based DSSCs fabricated at similar conditions.
Tin oxide (SnO2) is a candidate for applications requiring high electrical conductivity and optic... more Tin oxide (SnO2) is a candidate for applications requiring high electrical conductivity and optical transparency such as photoanode in dye-sensitized solar cells (DSCs) due to its high electron mobility and wider optical transparency than many other metal oxide semiconductors (MOS). However, DSCs employing SnO2 show significantly lower photoconversion efficiency, due to its intrinsic limitation such as lower conduction band energy and iso electric point, compared to that achieved by popular choices such as TiO2. A survey of literature shows a revived interest in SnO2 based DSCs recently, for example, strategies to (i) increase the dye uptake, (ii) increase its Fermi energy level, and (iii) reduce the recombination such as increasing surface roughness and novel morphologies towards (i), and doping of transition metals for (ii) and (iii). In response to these investments, SnO2 based DSCs showed similar VOC and superior current than that achieved by TiO2. We have undertaken a critical review on the progress made in overcoming its limitations and capitalizing its advantages to fabricate more efficient DSCs and observe that more investment is required to reduce the recombination in SnO2 for it to be emerged as an efficiency record holder in DSCs.
Tin oxide (SnO2) is a candidate for applications requiring high electrical conductivity and optic... more Tin oxide (SnO2) is a candidate for applications requiring high electrical conductivity and optical transparency, such as a photoanode in dye-sensitised solar cells (DSSCs), due to its higher electron mobility and wider optical transparency than many other metal oxide semiconductors (MOS), such as TiO2 and ZnO. However, DSSCs employing SnO2 show significantly lower photoconversion efficiency, compared to that achieved by popular choices, such as TiO2, due to its intrinsic limitations such as lower conduction band energy and isoelectric point. A survey of literature shows a revived interest in SnO2- based DSSCs, for example, strategies to (i) increase the dye uptake, (ii) increase its Fermi energy level, and (iii) reduce the recombination, such as by increasing surface roughness and novel morphologies towards (i), and doping of transition metals for (ii) and (iii). In response to these improvements, SnO2-based DSSCs showed similar open circuit voltage and superior short circuit current to that achieved by TiO2. We have undertaken a critical review on the progress made in overcoming the limitations and capitalising the advantages of SnO2 to fabricate more efficient DSSCs.We identify that more investment is required to reduce the recombination in SnO2 for it to emerge as an efficiency record holder in DSSCs
Photoanode plays a key role in dye sensitized solar cells (DSSCs) as a scaffold for dye molecules... more Photoanode plays a key role in dye sensitized solar cells (DSSCs) as a scaffold for dye molecules, transport
medium for photogenerated electrons, and scatters light for improved absorption. Herein, tin oxide
nanostructures unifying the above three characteristics were optimized by a hydrothermal process and
used as photoanode in DSSCs. The optimized morphology is a combination of hollow porous nanoparticles
of size 50 nm and micron sized spheres with BET surface area (up to 29 m2/g) to allow large
dye-loading and light scattering as well as high crystallinity to support efficient charge transport. The
optimized morphology gave the highest photovoltaic conversion efficiency (7.5%), so far achieved in
DSSCs with high open circuit voltage (700 mV) and short circuit current density (21 mA/cm2) employing
conventional N3 dye and iodide/triiodide electrolyte. The best performing device achieved an incident
photon to current conversion efficiency of 90%. The performance of the optimized tin oxide nanostructures
was comparable to that of conventional titanium based DSSCs fabricated at similar conditions.
Working electrode (WE) fabrication offers significant challenges in terms of achieving higheffici... more Working electrode (WE) fabrication offers significant challenges in terms of achieving highefficiency dye-sensitized solar cells (DSCs). We have combined the beneficial effects of vertical nanorods grown on conducting glass substrate for charge transport and mesoporous particles for dye loading and have achieved a high photoconversion efficiency of (η) > 11% with an internal quantum efficiency of ∼93% in electrode films of thickness ∼7 ± 0.5 μm. Controlling the interface between the vertical nanorods and the mesoporous film is a crucial step in attaining high η. We identify three parameters, viz., large surface area of nanoparticles, increased light scattering of the nanorod–nanoparticle layer, and superior charge transport of nanorods, that simultaneously contribute to the improved photovoltaic performance of the WE developed.
A number of nanocrystalline, mesoporous large area (~0.2-2 cm 2 ) dye-sensitized solar cells (DSS... more A number of nanocrystalline, mesoporous large area (~0.2-2 cm 2 ) dye-sensitized solar cells (DSSCs) are probed by electrochemical impedance spectroscopy measurements to realize their carrier dynamics such as charge transport resistance (RCT), electron diffusion coefficient (Dη), and electron lifetime (τn) by applying an equivalent electrical model. The experimental upshots reveal that the electron lifetime relates with the device physical parameters which was neglected in previous studies. It is also found that the RCT relates negatively with the device area i.e. it decrease upon increasing photo-exposed area. The observed lowering of current density (JSC) over a series of experiments upon increasing the photoelectrode area is attributed to the decrease in RCT. The charge carriers upon injection into semiconductor layer find increased diffusion pathways and eventually recombine with the hole species when characterized by lower carrier lifetime. The thickness of the electrode film does not play an effective role indicating that the dynamics of larger area DSSCs differs largely from those of a single cell. The experimental results available indicate that a nearly complete collection of charge carriers is possible in large area modules provided the physical dimensions of photoelectrode area are considered. The results from the study hints future directions to build high efficiency DSSC modules and further asserts considering the diffusion length in twodimensions while fabricating larger area cells.
Various one-dimensional nano-morphologies, such as multiporous nanofibers (MPNFs), porous nanofib... more Various one-dimensional nano-morphologies, such as multiporous nanofibers (MPNFs), porous nanofibers
(PNFs), and nanowires (NWs) of SnO2, are synthesized using electrospinning technique by controlling the tin
precursor concentration. The MPNFs have 8-fold higher surface area compared to the other
morphologies. Dye-sensitized solar cells (DSCs) were fabricated using these nanostructures as
photoanodes and their performance was compared. The MPNFs surpass the performance of PNFs and
NWs as well as conventional TiO2 paste. Record photoconversion efficiency (PCE) of 7.4% was realized
in MPNFs DSCs, which was twice to that achieved using PNFs (3.5%). Furthermore, the MPNFs showed
over >80% incident photon to current conversion efficiency (22% higher than that achieved by spherical
P25 TiO2 particles) and also demonstrated 3 times longer electron lifetime and electron diffusion
length. Owing to the possibility to produce large quantities using electrospinning technique, huge
commercial potential of SnO2 nanostructures, and promising results achieved herein, the MPNFs are
expected soon to be utilized in commercial devices.
Rutile nanorods based perovskite solar cells Stability of perovskite solar cells Lifetime of solu... more Rutile nanorods based perovskite solar cells Stability of perovskite solar cells Lifetime of solution processed solar cells Rutile nanowires TiCl 4 treatment in perovskite solar cells a b s t r a c t High efficiency is routinely reported in CH 3 NH 3 PbI 3Àx Cl x sensitized mesoscopic solar cells (PSCs) employing planar and scaffold architectures; however, a systematic comparison of their photovoltaic performance under similar experimental conditions and their long term stability have so far not been discussed. In this paper, we compare the performance and durability of PSCs employing these two device configurations and conclude that although a planar architecture routinely provides high initial photoconversion efficiency (PCE), particularly high open-circuit voltage (V OC ), a scaffold is crucial to achieve long term durable performance of such devices. In a comparative study of scaffold (rutile nanorods, NRs) vs. planar devices, the efficiency in latter dropped off by one order of magnitude in~300 h despite their similar initial PCE of~12%. We compared the performance and the durability of two types of scaffolds, i.e., pristine and TiCl 4 treated NRs, and observed that the pristine NRs showed >10% improvement in the PCE after~1300 h whereas the cells employing post-treated NR scaffold retained~60% of initial value. We address the origin of the different photovoltaic performance of planar and scaffold devices in the context of photoanode morphology and its possible effect on the cell durability.
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Papers by Qamar Wali
transparency, such as a photoanode in dye-sensitised solar cells (DSSCs), due to its higher electron
mobility and wider optical transparency than many other metal oxide semiconductors (MOS), such as
TiO2 and ZnO. However, DSSCs employing SnO2 show significantly lower photoconversion efficiency,
compared to that achieved by popular choices, such as TiO2, due to its intrinsic limitations such as lower
conduction band energy and isoelectric point. A survey of literature shows a revived interest in SnO2-
based DSSCs, for example, strategies to (i) increase the dye uptake, (ii) increase its Fermi energy level, and
(iii) reduce the recombination, such as by increasing surface roughness and novel morphologies towards
(i), and doping of transition metals for (ii) and (iii). In response to these improvements, SnO2-based
DSSCs showed similar open circuit voltage and superior short circuit current to that achieved by TiO2. We
have undertaken a critical review on the progress made in overcoming the limitations and capitalising
the advantages of SnO2 to fabricate more efficient DSSCs.We identify that more investment is required to
reduce the recombination in SnO2 for it to emerge as an efficiency record holder in DSSCs
medium for photogenerated electrons, and scatters light for improved absorption. Herein, tin oxide
nanostructures unifying the above three characteristics were optimized by a hydrothermal process and
used as photoanode in DSSCs. The optimized morphology is a combination of hollow porous nanoparticles
of size 50 nm and micron sized spheres with BET surface area (up to 29 m2/g) to allow large
dye-loading and light scattering as well as high crystallinity to support efficient charge transport. The
optimized morphology gave the highest photovoltaic conversion efficiency (7.5%), so far achieved in
DSSCs with high open circuit voltage (700 mV) and short circuit current density (21 mA/cm2) employing
conventional N3 dye and iodide/triiodide electrolyte. The best performing device achieved an incident
photon to current conversion efficiency of 90%. The performance of the optimized tin oxide nanostructures
was comparable to that of conventional titanium based DSSCs fabricated at similar conditions.
dye-sensitized solar cells (DSCs). We have combined the beneficial effects of vertical
nanorods grown on conducting glass substrate for charge transport and mesoporous particles for
dye loading and have achieved a high photoconversion efficiency of (η) > 11% with an internal
quantum efficiency of ∼93% in electrode films of thickness ∼7 ± 0.5 μm. Controlling the
interface between the vertical nanorods and the mesoporous film is a crucial step in attaining
high η. We identify three parameters, viz., large surface area of nanoparticles, increased light
scattering of the nanorod–nanoparticle layer, and superior charge transport of nanorods, that
simultaneously contribute to the improved photovoltaic performance of the WE developed.
(PNFs), and nanowires (NWs) of SnO2, are synthesized using electrospinning technique by controlling the tin
precursor concentration. The MPNFs have 8-fold higher surface area compared to the other
morphologies. Dye-sensitized solar cells (DSCs) were fabricated using these nanostructures as
photoanodes and their performance was compared. The MPNFs surpass the performance of PNFs and
NWs as well as conventional TiO2 paste. Record photoconversion efficiency (PCE) of 7.4% was realized
in MPNFs DSCs, which was twice to that achieved using PNFs (3.5%). Furthermore, the MPNFs showed
over >80% incident photon to current conversion efficiency (22% higher than that achieved by spherical
P25 TiO2 particles) and also demonstrated 3 times longer electron lifetime and electron diffusion
length. Owing to the possibility to produce large quantities using electrospinning technique, huge
commercial potential of SnO2 nanostructures, and promising results achieved herein, the MPNFs are
expected soon to be utilized in commercial devices.
transparency, such as a photoanode in dye-sensitised solar cells (DSSCs), due to its higher electron
mobility and wider optical transparency than many other metal oxide semiconductors (MOS), such as
TiO2 and ZnO. However, DSSCs employing SnO2 show significantly lower photoconversion efficiency,
compared to that achieved by popular choices, such as TiO2, due to its intrinsic limitations such as lower
conduction band energy and isoelectric point. A survey of literature shows a revived interest in SnO2-
based DSSCs, for example, strategies to (i) increase the dye uptake, (ii) increase its Fermi energy level, and
(iii) reduce the recombination, such as by increasing surface roughness and novel morphologies towards
(i), and doping of transition metals for (ii) and (iii). In response to these improvements, SnO2-based
DSSCs showed similar open circuit voltage and superior short circuit current to that achieved by TiO2. We
have undertaken a critical review on the progress made in overcoming the limitations and capitalising
the advantages of SnO2 to fabricate more efficient DSSCs.We identify that more investment is required to
reduce the recombination in SnO2 for it to emerge as an efficiency record holder in DSSCs
medium for photogenerated electrons, and scatters light for improved absorption. Herein, tin oxide
nanostructures unifying the above three characteristics were optimized by a hydrothermal process and
used as photoanode in DSSCs. The optimized morphology is a combination of hollow porous nanoparticles
of size 50 nm and micron sized spheres with BET surface area (up to 29 m2/g) to allow large
dye-loading and light scattering as well as high crystallinity to support efficient charge transport. The
optimized morphology gave the highest photovoltaic conversion efficiency (7.5%), so far achieved in
DSSCs with high open circuit voltage (700 mV) and short circuit current density (21 mA/cm2) employing
conventional N3 dye and iodide/triiodide electrolyte. The best performing device achieved an incident
photon to current conversion efficiency of 90%. The performance of the optimized tin oxide nanostructures
was comparable to that of conventional titanium based DSSCs fabricated at similar conditions.
dye-sensitized solar cells (DSCs). We have combined the beneficial effects of vertical
nanorods grown on conducting glass substrate for charge transport and mesoporous particles for
dye loading and have achieved a high photoconversion efficiency of (η) > 11% with an internal
quantum efficiency of ∼93% in electrode films of thickness ∼7 ± 0.5 μm. Controlling the
interface between the vertical nanorods and the mesoporous film is a crucial step in attaining
high η. We identify three parameters, viz., large surface area of nanoparticles, increased light
scattering of the nanorod–nanoparticle layer, and superior charge transport of nanorods, that
simultaneously contribute to the improved photovoltaic performance of the WE developed.
(PNFs), and nanowires (NWs) of SnO2, are synthesized using electrospinning technique by controlling the tin
precursor concentration. The MPNFs have 8-fold higher surface area compared to the other
morphologies. Dye-sensitized solar cells (DSCs) were fabricated using these nanostructures as
photoanodes and their performance was compared. The MPNFs surpass the performance of PNFs and
NWs as well as conventional TiO2 paste. Record photoconversion efficiency (PCE) of 7.4% was realized
in MPNFs DSCs, which was twice to that achieved using PNFs (3.5%). Furthermore, the MPNFs showed
over >80% incident photon to current conversion efficiency (22% higher than that achieved by spherical
P25 TiO2 particles) and also demonstrated 3 times longer electron lifetime and electron diffusion
length. Owing to the possibility to produce large quantities using electrospinning technique, huge
commercial potential of SnO2 nanostructures, and promising results achieved herein, the MPNFs are
expected soon to be utilized in commercial devices.