Synergistic Interaction of Dyes and Semiconductor Quantum Dots for Advanced Cascade Cosensitized Solar Cells

Abstract

Abstract.Here, we report a new procedure for the co-sensitization with quantum dots (QDs) and dyes for sensitized solar cell. Cascade co-sensitization of TiO 2 electrodes are obtained by the sensitization with CdS quantum dots (QDs) and zinc phthalocyanines (ZnPcs), in which ZnPcs containing sulfur atom have been specially designed to produce a cascade injection by attaching directly to QDs. This strategy causes a double synergetic interaction. This is the differentiating point of cascade co-sensitization in comparison with other approach in which dyes with conventional functionalization are employed, that pursue anchoring dyes to TiO 2 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 I ntroductionAn elegant strategy to improve the light-harvesting in photovoltaic devices is to use complementary light harvesters capable to produce panchromatic absorption. Here we have combined semiconductor quantum dots (QDs) and ad hoc designed phthalocyanines (Pcs) in order to prepare sensitized solar cells with enhanced efficiency. QDs are among potential key players in the next generation of photovoltaic devices [1] due to their low-cost solution-phase processability, large absorption cross sections, a spectrally tunable absorption onset (achieved via the quantum size effect), and enhanced multiple exciton generation or carrier multiplication. [2] After the first report on a certified QD solar cell, [3] a remarkable progress has been reached just in a couple of years obtaining certified power conversion efficiencies (PCEs) approaching 9%. [4] 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 3 On the other hand, Pcs are outstanding dye candidates in dye sensitized solar cells (DSSCs) due to their high extinction coefficient in the infrared spectral region and to their high thermal and chemical stabilities. [5] Pcs incorporated in DSSCs have achieved PCEs as high as 6.4 %, [6] still far away from the 12.75% PCE obtained by porphyrins, [7] their closest relatives. Light harvesting ability of QDs and Pcs can be enhanced by binding them, either covalent or supramolecular, producing a system capable to charge injection from both chromophores.However, the chemical combination of Pc rings to QDs has hardly been explored probably due to the difficulties to synthesize Pcs with the adequate anchoring groups. Until now just a few articles have been published where Pcs are covalently linked to QDs showing in most of the cases Förster resonance energy transfer (FRET) from QDs to Pcs. SiPc has been connected to CdSe QDs through axial ligation, [8] and also tetraminoZnPc [9] and unsymmetrically tris-tert-butyl-imidoZnPc [10] have been li...

Route to Improving Photovoltaics Based on CdSe/CdSexTe1–x Type-II Heterojunction Nanorods: The Effect of Morphology and Cosensitization on Carrier Recombination and Transport

“…Blas-Ferrando et al suggested a strategy of anchoring zinc phthalocyanine dyes onto CdS QDs by protecting thiol groups at the dye terminal from oxidation until just before they are released in the proximity of CdS QDs. 26 Esparza et al studied the effect of different loading methods on the performance of CdS-CdSe cosensitized solar cells where the presynthesized ∼10 nm long CdSe NRs were loaded on CdS-decorated TiO 2 electrode. 27 Our HNRs can be amenable to similar approaches, allowing extended light absorption compared to their single-component counterparts.…”

“…This approach of anchoring ex situ synthesized inorganic (or organic) sensitizers on the in situ pregrown semiconductor nanoparticle intermediate layer has been attempted to yield extended spectral absorption of incident light. Blas-Ferrando et al suggested a strategy of anchoring zinc phthalocyanine dyes onto CdS QDs by protecting thiol groups at the dye terminal from oxidation until just before they are released in the proximity of CdS QDs . Esparza et al.…”

Interaction between Colloidal Quantum Dots and Halide Perovskites: Looking for Constructive Synergies

“…There are previous examples of constructive combination of different families of materials, such as molecular dyes and colloidal QDs, that can provide enhanced charge photoinjection into TiO 2 41 and consequently increase the performance of the sensitized solar cells. 42 In this case, the obtained photocurrent is not just the consequence of the addition of materials absorbing at different light wavelengths. The internal recombination inside the QDs of the photogenerated carriers before being injected is highly suppressed because of a fast hole extraction toward the attached dye.…”

“…The internal recombination inside the QDs of the photogenerated carriers before being injected is highly suppressed because of a fast hole extraction toward the attached dye. 42 This is a clear example of a constructive synergy.…”

Excited‐State Charge Transfer in Covalently Functionalized MoS2 with a Zinc Phthalocyanine Donor–Acceptor Hybrid

“…Phthalocyanines (Pcs) are robust electron‐rich systems with a high capability to generate charge‐separated states. Due to this ability and their good chemical stability, Pcs have been covalently connected to a variety of electron acceptors and have been widely employed in photoinduced electron‐ and energy‐transfer processes. Although only the physisorption of Pcs on the basal plane of MoS 2 was reported recently, the covalent attachment on TMDs and the evaluation of their photophysical behavior have yet to be performed.…”