Fabrication, Characterization, and Optimization of CdS and CdSe Quantum Dot-Sensitized Solar Cells with Quantum Dots Prepared by Successive Ionic Layer Adsorption and Reaction

Abstract

CdS and CdSe quantum dot-sensitized solar cells (QDSSCs) were used for the study of determining the optimum preparation parameters that could yield the best solar cell performance. The quantum dots (QDs) were coated on the surface of mesoporous TiO2layer deposited on FTO substrate using the successive ionic layer adsorption and reaction (SILAR) method. In this method the QDs are allowed to grow on TiO2by dipping the TiO2electrode successively in two different solutions for predetermined times. This method allows the fabrication of QDs in a facile way. Three preparation parameters that control the QD fabrication were investigated: concentration of precursor solutions, number of dipping cycles (SILAR cycles), and dipping time in each solution. CdS based QDSSC showed optimum performance when the QDs were prepared from precursor solutions having the concentration of 0.10 M using 4 dipping cycles with the dipping time of 5 minutes in each solution. For CdSe QDSSC, the optimum performance was achieved with QDs prepared from 0.03 M precursor solutions using 7 dipping cycles with 30 s dipping time in each solution. The QDs deposited on TiO2surface were characterized using UV-vis absorption spectroscopy, FESEM, and TEM imaging.

Increased Quantum Dot Loading by pH Control Reduces Interfacial Recombination in Quantum-Dot-Sensitized Solar Cells

“…Thus, at higher SILAR cycles, QDs growing on the outer region of the TiO 2 film can actually block the pore channels to the inner regions, hindering any further QD nucleation on the interior. 67,68 This phenomenon is referred to here as pore-blocking. Strategies to improve the ion transport to and reaction with the anode surface include potential-induced solution deposition techniques, 69 improving the wetting of precursor solutions on the anode surface, 36 and sulfidizing the anode (for better growth of metal sulfide QDs).…”

“…An intrinsic difficulty with SILAR deposition on nanoporous substrates is that the precursor ions easily reach and deposit on the outer region of the nanoporous film, but have a more difficult time diffusing into the interior region of the film. Thus, at higher SILAR cycles, QDs growing on the outer region of the TiO 2 film can actually block the pore channels to the inner regions, hindering any further QD nucleation on the interior. , This phenomenon is referred to here as pore-blocking. Strategies to improve the ion transport to and reaction with the anode surface include potential-induced solution deposition techniques, improving the wetting of precursor solutions on the anode surface, and sulfidizing the anode (for better growth of metal sulfide QDs) .…”

Study of fabrication of fully aqueous solution processed SnS quantum dot-sensitized solar cell

“…It is also observed that bandgap energy is also increased with the increasing deposition concentration except for samples prepared from 0.5 M precursor concentration. The QD size was estimated from the absorption spectrum according to reported method [9]. The bulk bandgap energy for SnS is 1.3 eV, according to Deepa et al [19].…”

“…However, in CBD method, all the precursors are mixed together in one container, while in SILAR method, the precursors are separated. Thin film in SILAR method grows layer by layer, hence the film thickness can be controlled easily by varying the number of dipping cycle [9].…”

The effect of graphene quantum dots/ ZnS co‐passivation on enhancing the photovoltaic performance of CdS quantum dot sensitized solar cells

“…CdS QD layer was deposited by successive ionic layer adsorption and reaction (SILAR) method by soaking photoanodes in 0.06 M concentration of cadmium and sulfur anionic and cationic precursor solutions of CdCl 2 and Na 2 S at (1:1) ratio of methanol and water for eight cycles for a soaking period of 45 seconds. 37,[39][40][41] GQDs were sonicated for 30 minutes and coated on CdS loaded TiO 2 photoanode by direct absorption method. 42 The sensitized QD-loaded photoanode was dried by purging nitrogen (N 2 ) gas.…”