Effective MgO‐doped TiO2 nanoaerogel coating for crystalline silicon solar cells improvement

This study looks at investigating the influence of high surface area TiO₂ and MgO‐doped TiO₂ aerogel nanomaterials to improve the photovoltaic performance of monocrystalline silicon (mono‐Si) solar cells. TiO₂ and MgO‐doped TiO₂ anatase nanoaerogels were synthesized via a single‐step colloidal homogeneous precipitation sol‐gel method in a compact high‐pressure hydrogen reactor. TiO₂‐based nanoparticles were encapsulated in ethylene vinyl acetate resins, and the obtained composite solutions were screen printed on the textured surface of the cells. The specific surface area, microstructural, composition, and optical properties of the nanoaerogels were characterized by Brunaur‐Emmett‐Teller, X‐ray powder diffractometer, energy‐dispersive X‐ray spectroscopy, field emission transmission electron microscope, field emission scanning electron microscope, and ultraviolet‐visible spectrophotometry. We observed that the MgO‐doped TiO₂ (2% mol) nanoaerogel exhibited a much superior specific surface area (231 m²/g) compared with the undoped TiO₂ (154 m²/g). Experimental results showed that the calculated relative power conversion efficiency increased by 4.6% for the MgO‐doped TiO₂ coating and 3.4% for the undoped TiO₂ under a simulated one‐sun illumination.     

Recent advances in photo‐anode for dye‐sensitized solar cells: a review

Dye‐sensitized solar cell (DSSC) attracts immense interest in the last few decades due to its various attractive features such as low production cost, ease of fabrication and relatively high conversion efficiency, which make it a strong competitor to the conventional silicon‐based solar cell. In DSSC, photo‐anode performs two important functions, viz. governs the collection and transportation of photo‐excited electrons from dye to external circuit as well as acts as a scaffold layer for dye adsorption. The photo‐anode usually consists of wide band gap semiconducting metal oxides such as titanium dioxide (TiO₂) and zinc oxide (ZnO) deposited on the transparent conducting oxide substrates. The morphology and composition of the semiconductor oxides have significant impact on the DSSC photovoltaic performance. Therefore, enormous research efforts have been undertaken to investigate the influences of photo‐anode modifications on DSSC performance. The modifications can be classified into three categories, namely interfacial modification through the introduction of blocking and scattering layer, doping with non‐metallic anions and metallic cations and replacing the conventional mesoporous semiconducting metal oxide films with one‐dimensional or two‐dimensional nanostructures. In the present review, the previously mentioned modifications on photo‐anode are summarized based on the recent findings, with particular emphasis given to published works for the past 5 years. Copyright © 2017 John Wiley & Sons, Ltd.     

Reduced graphene oxide–titania nanocomposite‐modified photoanode for efficient dye‐sensitized solar cells

We report the successful application of reduced graphene oxide–titania (rGO–TiO₂) nanocomposite as an efficient photoanode for dye‐sensitized solar cell (DSSC). The DSSC assembled with the rGO–TiO₂‐modified photoanode demonstrated an enhanced solar to electrical energy conversion efficiency of 4.74% compared with the photoanode of DSSC composed with unmodified TiO₂ (2.19%) under full sunlight illumination (100 mW/cm², AM 1.5G) as a result of the better charge collection efficiency of rGO, which reduced the back electron transfer process. Influence of the rGO content on the overall efficiency was also investigated, and the optimal rGO content for TiO₂ was 0.5 mg. Further, the modification of rGO–TiO₂ on the compact layer TiO₂ surface led to an increase in efficiency to 5.83%. The superior charge collection and enhanced solar energy conversion efficiency of the rGO–TiO₂ nanocomposite makes it to be used as a promising alternative to conventional photoanode‐based DSSCs. Copyright © 2015 John Wiley & Sons, Ltd.     

A review on PEDOT‐based counter electrodes for dye‐sensitized solar cells

The dye‐sensitized solar cell (DSSC) is a promising alternative for the Si solar cell due to its low‐cost and easy fabrication. As a novel conductive polymer, poly(3,4‐ethylenedioxythiophene) (PEDOT) has attracted much attention for DSSCs. In this review article, the progress of PEDOT‐based counter electrodes for DSSCs is presented. First, the properties and structure of PEDOT are briefly described, and its feasibility as a DSSC counter electrode is demonstrated. Then, the effect of various treatments on the electrical conductivity and catalytic activity of PEDOT as well as its stability is examined. Furthermore, efficient and low‐cost composite counter electrodes consisting of PEDOT and other materials are deeply discussed. Finally, an outlook for PEDOT counter electrodes is provided. Copyright © 2014 John Wiley & Sons, Ltd.     

N‐doped titania powders prepared by different nitrogen sources and their application in quasi‐solid state dye‐sensitized solar cells

Nitrogen‐doped TiO₂ nanocrystalline particles are synthesized by a microwave‐assisted hydrothermal growth method using different amines (Dipropylamine, Diethanolamine and Ammonium hydroxide) as nitrogen sources. Characterization of the nanoparticles was performed with X‐ray diffraction, UV–vis diffuse reflectance spectroscopy, Field Emission Scanning Electron Microscopy and X‐ray Photoelectron Spectroscopy. The prepared N‐doped TiO₂ nanoparticles exhibit pure anatase phase with average diameter of 9 nm and reduced optical energy gap compared to undoped TiO₂. Immobilization of N‐doped and pure TiO₂ nanoparticles on SnO₂:F conductive glass substrates was successfully performed by using doctor‐blade technique and paste of the aforementioned nanoparticles. A series of N‐doped TiO₂ photoelectrodes with varying N dopant source and concentrations were fabricated for quasi‐solid state dye‐sensitized solar cells. The N‐doped solar cells achieve an overall conversion efficiency ranging from 4.0 to 5.7% while undoped TiO₂ showed 3.6%. The basic difference to the electrical performance of the cells is focused to the enhancement in the current density of N‐doped TiO₂‐based cells which was from 11% to 58% compared with undoped TiO₂ cells. Current densities were directly proportional with nitrogen doping level in TiO₂ lattice which differs depending on the amine source nature such as basicity differences, hydrogen bonding abilities and steric inherences. Copyright © 2013 John Wiley & Sons, Ltd.     

Effects of graphene counter electrode and CdSe quantum dots in TiO2 and ZnO on dye‐sensitized solar cell performance

Fabrication and performance study of dye‐sensitized solar cells using different counter electrodes and photoanodes is reported. Spin coated, E‐beam coated platinum, and graphene electrodes were used as counter electrodes. Different combinations of TiO₂ nanoparticle and ZnO nanorods (NRs) with CdSe quantum dots were prepared and used as photoanodes. The photoanodes comprising of both ZnO NRs and TiO₂ nanoparticles have shown improved performances in short‐circuit current density and open‐circuit voltage comparing the devices fabricated using only ZnO NR or TiO₂ nanoparticles. The inclusion of CdSe quantum dots has been found to increase the performance of dye‐sensitized solar cell for all the photoanodes. In case of counter electrodes, the cells fabricated with graphene showed improved performance. Copyright © 2014 John Wiley & Sons, Ltd.