Processing and characterization of a TiO<sub>2</sub> paste based on small particle size powders for dye‐sensitized solar cell semi‐transparent photo‐electrodes

Schulz-Ruhtenberg

Progress in Photovoltaics

et al. 2012

We have analysed and optimised a laser process for the sintering of the TiO2 layers in dye solar cells (DSCs). Through a thermographic characterisation of the process, we show that it is possible to scale and process large areas uniformly (16 cm2). We fabricated DSCs with nanocrystalline (nc)‐TiO2 films sintered by using pulsed ultraviolet laser with an average output power P varying from 1 W to 7 W whilst mainting a constant power conversion efficiency η. The highest efficiency reached for a laser sintered DSC was 7%. The time required to sinter 1 m2 of nc‐TiO2 film was found to decrease hyperbolically with P, which is important for determining process takt times. We quantified the embodied energy (EE) required to sinter 1 m2 of the active TiO2 layer for a variety of different processes, and found that the EE for the laser sintering process with a system wall plug efficiency of 3.5% to be competitive with the more conventional oven and belt furnace treatments. We outline the main features required from a laser system to carry out an efficient, energetically favourable and industrially applicable automated process with competitive throughput. Copyright © 2012 John Wiley & Sons, Ltd.

Section: Processing Times For Raster Scanning Laser Sinteringmentioning

confidence: 99%

Laser processing of TiO₂ films for dye solar cells: a thermal, sintering, throughput and embodied energy investigation

Schulz-Ruhtenberg

Progress in Photovoltaics

et al. 2012

“…The paste composition is described elsewhere. [ 21,37 ] The nc-TiO 2 fi lm was removed irradiating the substrate via a Gaussian ( M 2 = 1.3) pulsed laser (repetition rate f = 400 kHz, pulse length τ = 7 ps) emitting at λ = 515 nm (frequency doubled Yb:Yag disk laser) and delivering a maximum average output power P max = 23 W (Trumpf True Micro 5250). Both substrates were irradiated with the laser beam facing the uncoated side and fi xing the focus (produced by a 250 mm f-theta lens) at the nc-TiO 2 /FTO interface.…”

Section: Discussionmentioning

confidence: 99%

Taking Temperature Processing Out of Dye‐Sensitized Solar Cell Fabrication: Fully Laser‐Manufactured Devices

Advanced Energy Materials

Schulz-Ruhtenberg

et al. 2014

Self Cite

a light-absorbing dye, an electrolyte and a platinized conductive top substrate.Different from more established photovoltaic technologies, standard, industrial, reliable, highly automated, and effi cient fabrication procedures have yet to be fully defi ned and integrated for DSCs. Most fabrication steps currently entail the use of printing processes (such as screen printing of the nc-TiO 2 and Pt precursor layers) and of high temperature treatments in ovens to fi re the nc-TiO 2 and Pt precursor fi lms at 400-550 °C. Alternative low-tempteature approaches suitable for plastic substrates have been intensively studied and reported in the literature. [8][9][10][11][12] The nc-TiO 2 fi lm sensitization is usually achieved by soaking the fi lms in a dye solution, and devices are sealed by means of a thermoplastic gasket (heated and pressed at around 100 °C) followed by electrolyte injection.Lasers have recently started to be utilized in DSCs processing. [13][14][15][16][17][18] In particular, we have reported an effi cient, effective, scalable, and low embodied energy sintering procedure for the nc-TiO 2 fi lm. [19][20][21] Here we demonstrate that all the primary DSC manufacturing steps that required temperature treatments and in particular, sintering of the TiO 2 fi lm, curing of the Pt precursor, and device sealing, can be successfully and effi ciently carried out via laser assisted processes controlled by means of raster scanning systems (RSLSs). We believe this to be the fi rst demonstration of a device which is also effi cient and durable, where absolutely no temperature treatments were applied (all replaced by laser processing) together with a method for the defi nition of the cell pattern. The new processes were introduced while maintaining an uncompromising level of performance (6% conversion effi ciency) and durability (lifetime), the same as devices manufactured by conventional processes.We developed laser fabrication processes for the 1) patterning of the active layer, 2) sintering of the TiO 2 layer, 3) curing of the Pt precursor catalyst, and 4) encapsulation via a perimeter thermoplastic gasket. We present each of these developments here. Results and Discussion Laser-Patterning and Laser-Sintering of nc-TiO 2 FilmsAn important feature of DSC technology consists in the use of printing/masking procedures to defi ne the main active Pt and

“…Acetic acid reduces the aggregation of the particles [21]- [23], while water and acid work together to prevent cracks in the layer [21], [24]. The solution was transferred in a beaker with 10 g of α-terpineol and 15 g of 10% ethyl-cellulose solution in ethanol.…”

Section: B Spacer and Counter-electrodementioning

confidence: 99%

“…The solution was transferred in a beaker with the cellulose thickener Triton-X 100 (5 g) and consequently stirred and sonicated [24], [26], [27].…”

Section: B Spacer and Counter-electrodementioning

confidence: 99%

Fabrication of Spacer and Catalytic Layers in Monolithic Dye-Sensitized Solar Cells

Riccitelli²,

et al. 2013

IEEE J. Photovoltaics

Self Cite

Over the past few years, dye-sensitized solar cell (DSC) research has been focused on the material and process cost\ud reduction, and on the electronics integration of the devices.Monolithic design is one of the most promising DSC architectures for\ud mass production, because it allows the elimination of one conductive substrate and offers the possibility of printing layer-by-layer\ud the materials that compose the structure. In this study, the formulation, the realization, and the processing of the spacer and the\ud catalyst layers are proposed, and the relative performance in terms of J–V characteristics, incident photon to current conversion efficiency, and impedance analysis of the device with the optimized material thickness is reported. The optimized profile of the overall structure permits us to obtain masked cells with a conversion efficiency of about 5% with no chemical treatment