Suppressed recombination in quantum dot-sensitized solar cells with blocking layers on FTO substrates.

The compact and thin TiO2 blocking layers (c-TiO2) were formed on F-doped SnO2 (FTO) substrate in quantum dots-sensitized solar cells (QSSCs) by chemical deposition. The c-TiO2 layers induced indirect contact between electrolyte and FTO electrode, which reduced leakage in QSSCs. The QSSCs showed power conversion efficiency (Eff) of 3.85% in the presence of c-TiO2 layers which leads to 21% improved compared to that without c-TiO2 layers (Eff = 3.18%). The presence of the c-TiO2 layers in QSSCs also improved the stability under illumination.

Method to protect charge recombination in the back-contact dye-sensitized solar cell.

We prepared a back-contact dye-sensitized solar cell and investigated effect of the sputter deposited thin TiO2 film on the back-contact ITO electrode on photovoltaic property. The nanocrystalline TiO2 layer with thickness of about 11 µm formed on a plain glass substrate in the back-contact structure showed higher optical transmittance than that formed on an ITO-coated glass substrate, which led to an improved photocurrent density by about 6.3%. However, photovoltage was found to decrease from 817 mV to 773 mV. The photovoltage recovered after deposition of a 35 nm-thick thin TiO2 film on the surface of the back-contact ITO electrode. Little difference in time constant for electron transport was found for the back-contact ITO electrodes with and without the sputter deposited thin TiO2 film. Whereas, time constant for charge recombination increased after introduction of the thin TiO2 film, indicating that such a thin TiO2 film protected back electron transfer, associated with the recovery of photovoltage. As the result of the improved photocurrent density without deterioration of photovoltage, the back-contact dye-sensitized solar cell exhibited 13.6% higher efficiency than the ITO-coated glass substrate-based dye-sensitized solar cell.

Influence of nylon 6 in I3(-)/I(-) redox electrolyte on the photovoltaic performance and stability of dye-sensitized solar cells.

Nylon 6 fibers are used, for the first time, in dye-sensitized solar cells (DSSCs). The overall energy conversion efficiency obtained with 0.18 M nylon 6 reaches 6.2%, which is comparable to that (6.7%) obtained without adding nylon 6 on the day of cell fabrication. However, it is found that the long-term stability of the DSSCs with nylon 6 is superior to that of a reference electrolyte as a result of the complexation of nylon 6 with I(3)(-). Furthermore, nylon 6 is found to be a corrosion inhibitor for silver metal in the electrolyte containing I(3)(-).

Photocurrent enhancement of dye-sensitized solar cells owing to increased dye-adsorption onto silicon-nanoparticle-coated titanium-dioxide films.

The inverse-micellar preparation of Si nanoparticles (Nps) was improved by utilizing sodium naphthalide. The Si Nps were subsequently functionalized with 4-vinylbenzoic acid for their attachment onto TiO(2) films of dye-sensitized solar cells (DSSCs). The average diameter of the COOH-functionalized Si (Si-COOH) Nps was 4.6(±1.7) nm. Depth profiling by secondary-ion mass spectrometry revealed that the Si Nps were uniformly attached onto the TiO(2) films. The number of Ru(II) dye molecules adsorbed onto a TiO(2) film that was treated with the Si-COOH Nps was 42 % higher than that on the untreated TiO(2) film. As a result, DSSCs that incorporated the Si-COOH Nps exhibited higher short-circuit photocurrent density and an overall energy-conversion efficiency than the untreated DSSCs by 22 % and 27 %, respectively. This enhanced performance, mostly owing to the intramolecular charge-transfer to TiO(2) from the dye molecules that were anchored to the Si-COOH Nps, was confirmed by comparing the performance with two different Ru(II) -bipyridine dyes (N719 and N749).