Solution processed graphene structures for perovskite solar cells

Organometallic trihalide perovskite light absorber based solar cells have drawn increasing attention because of their recent rapid increase in power conversion efficiency (PCE). These photovoltaic cells have relied significantly on transparent conducting oxide (TCO) electrodes which are costly and brittle. Herein, solution processed transparent conductive graphene films (TCGFs) are utilized, for the first time, as an alternative to traditional TCO electrodes at the electron collecting layer in perovskite solar cells (PSCs). By investigating and optimizing the trade-off between transparency and sheet resistance (Rs) of the graphene films, a PCE of 0.62% is achieved. This PCE is further improved to 0.81% by incorporating graphene structures into both compact and mesoporous TiO2 layers of the solar cell. We anticipate that the present study will lead to further work to develop graphene-based transparent conductive electrodes for future solar cell devices

Sulfur-doped graphene with iron pyrite (FeS 2 ) as an efficient and stable electrocatalyst for the iodine reduction reaction in dye-sensitized solar cells

As an alternative to platinum (Pt), hybrid electrocatalysts based on sulfur-doped graphene with FeS2 microspheres (SGN-FeS2) were used as a counter electrode (CE) in dye-sensitized solar cells (DSSCs). Benefiting from the high conductivity of SGN and excellent electrocatalytic activity of the FeS2, the bifunctional hybrid electrocatalyst-based device displays a power conversion efficiency (PCE) of 8.1%, which is comparable to that (8.3%) of traditional Pt CE-based DSSC, while also exhibiting excellent stability in ambient conditions. These characteristics, in addition to its low-cost and facile preparation, make the SGN–FeS2 hybrid an ideal CE material for DSSCs

Carbon nanotubes in TiO₂ nanofiber photoelectrodes for high-performance perovskite solar cells

1D semiconducting oxides are unique structures that have been widely used for photovoltaic (PV) devices due to their capability to provide a direct pathway for charge transport. In addition, carbon nanotubes (CNTs) have played multifunctional roles in a range of PV cells because of their fascinating properties. Herein, the influence of CNTs on the PV performance of 1D titanium dioxide nanofiber (TiO2 NF) photoelectrode perovskite solar cells (PSCs) is systematically explored. Among the different types of CNTs, single-walled CNTs (SWCNTs) incorporated in the TiO2 NF photoelectrode PSCs show a significant enhancement (≈40%) in the power conversion efficiency (PCE) as compared to control cells. SWCNTs incorporated in TiO2 NFs provide a fast electron transfer within the photoelectrode, resulting in an increase in the short-circuit current (J sc) value. On the basis of our theoretical calculations, the improved open-circuit voltage (V oc) of the cells can be attributed to a shift in energy level of the photoelectrodes after the introduction of SWCNTs. Furthermore, it is found that the incorporation of SWCNTs into TiO2 NFs reduces the hysteresis effect and improves the stability of the PSC devices. In this study, the best performing PSC device constructed with SWCNT structures achieves a PCE of 14.03%

Nanocarbons for mesoscopic perovskite solar cells

Organic-inorganic halides based perovskite solar cells (PSCs) have attracted a great deal of attention from the photovoltaic (PV) research community due to the extremely rapid increases in efficiencies observed over the past few years. The PSC is an extension of dye-sensitised solar cells and has reached an energy conversion efficiency of 19.3% by mid-2014. However, PSCs do have some disadvantages such as use of expensive metal electrodes, the high temperature required during production and poor stability when in use. There is no doubt that research with carbon nanomaterials will play an important role in understanding and solving the issues currently observed in PSCs, as they consistently have been shown to improve performance in a wide range of energy related applications. The present review (i) provides a brief introduction to PSC development; (ii) highlights the notable achievements of PSCs; (iii) particularly focuses on the use of nanocarbon in mesoscopic PSCs and (iv) predicts and suggests a roadmap for the future application of carbon materials in this emerging technology

Tin oxide light-scattering layer for Titania Photoanodes in dye-sensitized solar cells

High-performance dye-sensitized solar cell (DSSC) devices rely on photoanodes that possess excellent light-harvesting capability and high surface area for sufficient dye adsorption. In this work, morphologically controlled SnO2 microstructures have been synthesized and used as an efficient light backscattering layer on top of the nanocrystalline TiO2 layer to prepare a double-layered photoanode. By optimizing the thickness of both the TiO2 bottom layer and SnO2 top layer, a high power conversion efficiency (PCE) of 7.8% is achieved, demonstrating a ~38% enhancement in the efficiency when compared to a nanocrystalline TiO2-only photoanode (5.6%). We attribute this efficiency improvement to the superior light backscattering capability of SnO2 microstructures

Incorporation of graphene into SnO2 photoanodes for dye-sensitized solar cells

© 2016 Elsevier B.V.In dye-sensitized solar cell (DSSC) photoanodes, tin dioxide (SnO2) structures present a promising alternative semiconducting oxide to the conventional titania (TiO2), but they suffer from poor photovoltaic (PV) efficiency caused by insufficient dye adsorption and low energy value of the conduction band. A hybrid structure consisting of SnO2 and reduced graphene oxide (SnO2-RGO) was synthesized via a microwave-assisted method and has been employed as a photoanode in DSSCs. Incorporation of RGO into the SnO2 photoanode enhanced the power conversion efficiency of DSSC device by 91.5%, as compared to the device assembled without RGO. This efficiency improvement can be attributed to increased dye loading, enhanced electron transfer and addition of suitable energy levels in the photoanode. Finally, the use of RGO addresses the major shortcoming of SnO2 when employed as a DSSC photoanode, namely poor dye adsorption and slow electron transfer rate

Single-walled carbon nanotubes enhance the efficiency and stability of mesoscopic perovskite solar cells

Carbon nanotubes are 1D nanocarbons with excellent properties and have been extensively used in various electronic and optoelectronic device applications including solar cells. Herein, we report a significant enhancement in the efficiency and stability of perovskite solar cells (PSCs) by employing single-walled carbon nanotubes (SWCNTs) in the mesoporous photoelectrode. It was found that SWCNTs provide both rapid electron transfer and advantageously shifts the conduction band minimum of the TiO2 photoelectrode and thus enhances all photovoltaic parameters of PSCs. The TiO2-SWCNTs photoelectrode based PSC device exhibited a power conversion efficiency (PCE) of up to 16.11%, while the device fabricated without SWCNTs displayed an efficiency of 13.53%. More importantly, we found that the SWCNTs in the TiO2 nanoparticles (TiO2 NPs) based photoelectrode suppress the hysteresis behavior and significantly enhance both the light and long-term storage stability of the PSC devices. The present work provides important guidance for future investigations in utilizing carbonaceous materials for solar cells

Back cover: Solar RRL 3-4∕2017

Dye-sensitized solar cells (DSSCs) were first reported almost thirty years ago and considerable efforts have gone into improving every component in that time. Despite all these efforts, the improvements from the early designs have been marginal and there are still considerable issues to overcome. One such issue is the use of platinum (Pt) as the counter electrode due to its expense and catalytic properties. Here, Batmunkh et al. (Article No. 1700011) used hybrid electrocatalysts based on sulfur-doped graphene with FeS2 microspheres (SGN-FeS2) as a counter electrode (CE) in DSSCs, instead of Pt. Because of the high conductivity of SGN and excellent electrocatalytic activity of the FeS2, the bifunctional hybrid electrocatalyst based device displays a power conversion effi ciency (PCE) comparable to that of traditional Pt CE based DSSC, while also exhibiting excellent stability in ambient conditions. These characteristics, in addition to the fact that the new hybrid is relatively cheap and easy to prepare, mean the SGN-FeS2 hybrid is an ideal CE material for DSSCs

Back cover: Solar RRL 3-4∕2017

Dye-sensitized solar cells (DSSCs) were first reported almost thirty years ago and considerable efforts have gone into improving every component in that time. Despite all these efforts, the improvements from the early designs have been marginal and there are still considerable issues to overcome. One such issue is the use of platinum (Pt) as the counter electrode due to its expense and catalytic properties. Here, Batmunkh et al. (Article No. 1700011) used hybrid electrocatalysts based on sulfur-doped graphene with FeS2 microspheres (SGN-FeS2) as a counter electrode (CE) in DSSCs, instead of Pt. Because of the high conductivity of SGN and excellent electrocatalytic activity of the FeS2, the bifunctional hybrid electrocatalyst based device displays a power conversion effi ciency (PCE) comparable to that of traditional Pt CE based DSSC, while also exhibiting excellent stability in ambient conditions. These characteristics, in addition to the fact that the new hybrid is relatively cheap and easy to prepare, mean the SGN-FeS2 hybrid is an ideal CE material for DSSCs

Sulfur-doped graphene with iron pyrite (FeS 2 ) as an efficient and stable electrocatalyst for the iodine reduction reaction in dye-sensitized solar cells

As an alternative to platinum (Pt), hybrid electrocatalysts based on sulfur-doped graphene with FeS2 microspheres (SGN-FeS2) were used as a counter electrode (CE) in dye-sensitized solar cells (DSSCs). Benefiting from the high conductivity of SGN and excellent electrocatalytic activity of the FeS2, the bifunctional hybrid electrocatalyst-based device displays a power conversion efficiency (PCE) of 8.1%, which is comparable to that (8.3%) of traditional Pt CE-based DSSC, while also exhibiting excellent stability in ambient conditions. These characteristics, in addition to its low-cost and facile preparation, make the SGN–FeS2 hybrid an ideal CE material for DSSCs