Molang Cai

Efficient panchromatic inorganic–organic heterojunction solar cells with consecutive charge transport tunnels in hole transport material

A simple solution-processing method was employed to fabricate panchromatic mp-TiO2/CH3NH3PbI3/P3HT-MWNT/Au solar cells. MWNTs in a P3HT-MWNT composite acted as efficient nanostructured charge transport tunnels and induce crystallization of P3HT, hence significantly enhancing the conductivity of the composite. The fill factor of the hybrid solar cells was greatly enhanced by 26.7%.

Multiple adsorption of tributyl phosphate molecule at the dyed-TiO2/electrolyte interface to suppress the charge recombination in dye-sensitized solar cell

Electron recombination and dye aggregation at the dyed-TiO2/electrolyte interface are still problems in dye-sensitized solar cell (DSC) research. In this paper, tributyl phosphate (TBpp) as a special additive to modify the dyed-TiO2/electrolyte interface was introduced to enhance the photovoltaic performance. The adsorption mode of TBpp and the interaction between cis-dithiocyanate-N,N′-bis-(4-carboxylate-4-tetrabutylammonium carboxylate-2,2′-bi-pyridine) ruthenium(II) (N719) and TBpp were investigated. It was found that one TBpp parent molecule split into several smaller fragments and formed four anchoring modes on the TiO2 surface. It was very interesting that the molecular cleavage of TBpp and adsorption of N719 assisted each other on the sensitized TiO2 surface. The fragments distributed around N719 result in steric hindrance, consequently hydrogen-bonding among N719 molecules was decreased. The unstable type N719 transformed into stable type N719 accompanied by molecular cleavage of TBpp and the N719 aggregation was reduced. Furthermore, these new fragments were multiply adsorbed on the non-sensitized TiO2 surface to form an insulating barrier layer. Therefore, the electron recombination at the dyed-TiO2/electrolyte interface was restrained. Besides the change of surface configuration, the TiO2 band edge negatively shifted and the rate of electron transport in the TiO2 films decreased with the addition of TBpp. As a result, an increase in the photoelectric conversion efficiency (η) was obtained of almost 40%.

Surface modification of TiO2 by an ionic liquid electrolyte in dye-sensitized solar cells using a molecular insulator

A factor that limits the performance of dye-sensitized solar cells (DSC) based on ionic liquids is the disappearance of electron density due to electron recombination at the Dyed-TiO2/electrolyte interface. Adding an additive to the electrolyte can affect processes related to the kinetics of the electron recombination. In this paper a novel solid state additive, 1,2-dimethylimidazolium-3-propylsulfonate (DMImBS), was synthesized in an autoclave and directly applied to a DSC based on an ionic liquid electrolyte to form a molecular insulator layer. It was found that the presence of DMImBS in the ionic liquid electrolyte enhances both the open circuit photovoltage (Voc) and fill factor (FF) without significant penalizing the photocurrent (Jsc), as well as significantly increasing the power output of the DSC. This is suggested to be mainly due to the passivation of surface states, which effectively reduces electron recombination and restrains the Li+ intercalation. The device based on DMImBS also showed outstanding stability under prolonged light soaking at 50 °C, maintaining 100% photovoltaic efficiency.

The Light Attracting Effect of Pyridine Derivatives Based Quasi-Solid Electrolyte in Dye-Sensitized Solar Cell.

The pyridine derivatives are added into acetonitrile based electrolyte to establish framework, then form the quasi solid electrolyte. The ion diffusion of cetylpyridinium chloride and cetylpyridinium bromide based electrolytes is enhanced comparing with the ion diffusion of reference acetonitrile electrolyte. The ordered structure of cetylpyridinuium chloride quasi solid electrolyte has been observed by SEM images. Light scattering effect of cetylpyridinuium chloride quasi solid electrolyte is evidenced by the larger resulted by transmitted and scattered spectra. The light harvesting efficiency of device based on C16Cl is much higher than acetonitrile based device. The cell efficiency of C16Cl and C16Br based device are 5.72% and 6.02%, which are 41% and 48% higher than acetonitrile liquid electrolyte based device. The C16l based device produces low cell efficiency 2.06%, which is 49% decrease compare to the blank device due to the limitation of iodide-triodide transportation in the iodide framework.