Huicheng Sun

Dye-sensitized solar cells with NiS counter electrodes electrodeposited by a potential reversal technique

Nickel sulfides have been, for the first time, electrodeposited on transparent conductive glass by a facile periodic potential reversal (PR) technique to supersede Pt counter electrodes (CEs) of dye-sensitized solar cells (DSCs). The composition and electrochemical catalytic activity of the nickel sulfide films prepared by PR technique are different from those of the ones deposited by the commonly used potentiostatic (PS) technique. PR technique produces transparent single-component NiS, while co-deposition of Ni and NiS is found in the opaque films prepared by PS method. The nickel sulfide deposited by PR technique shows high catalytic activity for the reduction of I3− to I− in a DSC. DSC with the CE deposited by PR technique performs much better (6.82%) than that by PS method (3.22%), and is comparable to the device with conventional Pt coated CE (7.00%).

Composite counter electrode based on nanoparticulate PbS and carbon black: towards quantum dot-sensitized solar cells with both high efficiency and stability.

PbS/carbon black (CB) composite counter electrode (CE) has been fabricated by a low cost and low temperature processable method using the wet chemistry synthesized PbS nanoparticles. The nanosized PbS in the composite CE provides a large area of catalytic sites, and the chain-type CB framework acts as an excellent electrical tunnel for fast electron transport from an external circuit to highly catalytic PbS nanoparticles. The optimized PbS/CB composite CE shows a charge transfer resistance (R(CT)) as low as 10.28 Ω cm², which is an order of magnitude lower than the value obtained in the previous study on pure PbS CE. The CdS/CdSe quantum dot-sensitized solar cells with the PbS/CB composite CE achieve a photovoltaic conversion efficiency of 3.91% and no degradation of the efficiency over 1000 h under room conditions.

Quasi-solid-state dye-sensitized solar cell fabricated with poly (β-hydroxyethyl methacrylate) based organogel electrolyte

A novel freestanding poly (β-hydroxyethyl methacrylate), PHEMA-based organogel electrolyte is developed simply by optimization of the solution polymerization in the same solvent as the organic electrolyte for dye-sensitized solar cells (DSCs). The room temperature ionic conductivity of the gel electrolyte is 4.54 × 10−3 S cm−1, and the conduction behavior can be well described by the free volume model. The quasi-solid-state dye-sensitized solar cell fabricated with this PHEMA-based polymer gel electrolyte can present high energy conversion efficiency up to 7.5%. Preliminary long-term stability test further reveals that this quasi-solid-state electrolyte exhibits good stability after 1000 h thermal test in comparison with the DSCs based on corresponding liquid electrolyte.

Carbon nanotube counter electrode for high-efficient fibrous dye-sensitized solar cells

High-efficient fibrous dye-sensitized solar cell with carbon nanotube (CNT) thin films as counter electrodes has been reported. The CNT films were fabricated by coating CNT paste or spraying CNT suspension solution on Ti wires. A fluorine tin oxide-coated CNT underlayer was used to improve the adherence of the CNT layer on Ti substrate for sprayed samples. The charge transfer catalytic behavior of fibrous CNT/Ti counter electrodes to the iodide/triiodide redox pair was carefully studied by electrochemical impedance and current-voltage measurement. The catalytic activity can be enhanced by increasing the amount of CNT loading on substrate. Both the efficiencies of fibrous dye-sensitized solar cells using paste coated and sprayed CNT films as counter electrodes are comparative to that using Pt wires, indicating the feasibility of CNT/Ti wires as fibrous counter electrode for superseding Pt wires.

Front-side illuminated CdS/CdSe quantum dots co-sensitized solar cells based on TiO2 nanotube arrays

We fabricated a front-side illuminated CdS/CdSe quantum dots co-sensitized solar cell based on TiO(2) nanotube arrays. The freestanding TiO(2) nanotube arrays were first detached from anodic oxidized Ti foils and then transferred to the fluorine-doped tin oxide to form photoanodes. An opaque Cu(2)S with high electrochemical activity was used as the counter electrode. A photovoltaic conversion efficiency as high as 3.01% under one sun illumination has been achieved after optimizing the deposition time of CdSe quantum dots and the length of the TiO(2) nanotube arrays. It is observed that the power conversion efficiency of quantum dots sensitized solar cells from the front-side illumination mode (3.01%) is much higher than that of the back-side illumination mode (1.32%) owing to the poor catalytic activity of Pt to polysulfide electrolytes and light absorption by the electrolytes for the latter.

Highly efficient fibrous dye-sensitized solar cells based on TiO2 nanotube arrays

The structure of fibrous dye-sensitized solar cells, which were constructed by a TiO(2) nanotube array on Ti wire as the photoanode twisted by a Pt wire counter electrode, has been first systematically investigated by accurately controlling the thread pitch distance of screwed Pt wire. It has been revealed that the thread pitch will strongly influence the photovoltaic performance and kinetic processes in fibrous solar cells. The effect of the length of the TiO(2) nanotube on cell performance has also been discussed. After optimization, a relatively universal optimized thread pitch value of 1 mm for fibrous DSCs has been proved and the light-to-electricity conversion efficiency has been remarkably improved to 5.84%.