Quantum dot-sensitized solar cells incorporating nanomaterials

Abstract

Quantum dot-sensitized solar cells (QDSSCs) are interesting energy devices because of their (i) impressive ability to harvest sunlight and generate multiple electron/hole pairs, (ii) ease of fabrication, and (iii) low cost. The power conversion efficiencies (η) of most QDSSCs (typically <4%) are, however, less than those (up to 12%) of dye-sensitized solar cells, mainly because of narrow absorption ranges and charge recombination occurring at the QD-electrolyte and TiO(2)-electrolyte interfaces. To further increase the values of η of QDSSCs, it will be necessary to develop new types of working electrodes, sensitizers, counter electrodes and electrolytes. This Feature Article describes the nanomaterials that have been used recently as electronic conductors, sensitizers and counter electrodes in QDSSCs. The nature, size, morphology and quantity of these nanomaterials all play important roles affecting the efficiencies of electron injection and light harvesting. We discuss the behavior of several important types of semiconductor nanomaterials (sensitizers, including CdS, Ag(2)S, CdSe, CdTe, CdHgTe, InAs and PbS) and nanomaterials (notably TiO(2), ZnO and carbon-based species) that have been developed to improve the electron transport efficiency of QDSSCs. We point out the preparation of new generations of nanomaterials for QDSSCs and the types of electrolytes, particularly iodide/triiodide electrolytes (I(-)/I(3)(-)), polysulfide electrolytes (S(2-)/S(x)(2-)), and cobalt redox couples ([Co(o-phen)(3)(2+)/(3+)]), that improve their lifetimes. With advances in nanotechnology, we foresee significant improvements in the efficiency (η > 6%) and durability (>3000 h) of QDSSCs.

Towards efficient photoinduced charge separation in carbon nanodots and TiO2 composites in the visible region

“…24,25 The surface defects are unstable and dissipative in energy, which are unfavorable for efficient electron injection in PVs. 23,[26][27][28] In addition, the reported CDs are generally passivated with insulating long chain molecules, 10,12,29 which act as tunneling barriers and are against efficient electron injection and well performing CD-based optoelectronic devices. 22,30 To realize efficient CD-sensitized TiO 2 PVs under sunlight, the CDs should exhibit intrinsic absorption in the visible region and be integrated effectively with TiO 2 .…”

High performance PbS Quantum Dot Sensitized Solar Cells exceeding 4% efficiency: the role of metal precursors in the electron injection and charge separation

“…In the last few years, the use of inorganic semiconductors as alternative sensitizers for Dye Sensitized Solar Cells (DSCs) has experienced an impressive enhancement, [3][4][5][6][7][8][9] reflected in the continuous growth of the number of scientific papers published. The efficiencies obtained with these sensitizers remain below those reported for molecular dyes.…”

“…However, the extremely easy preparation based on solution chemistry and the high potentiality (high extinction coefficient, 10 tunable band gap in the quantum confinement regime, 11 and large intrinsic dipole moment 12 ) of these systems have boosted the research in this field. [3][4][5][6][7][8][9] The recent reports of perovskite semiconductor on nanoporous matrix with outstanding efficiencies, around 10%, 13,14 will undoubtedly enhance the interest in inorganic semiconductors as light harvesting materials in nanostructured devices.…”

Co-sensitized TiO2 Photoelectrodes by Multiple Semiconductors (Pbs/Pb0.05Cd0.95S/Cds)to Enhance the Performance of a Solar Cell

“…Recently, many new strategies, especially the surface and interface treatment, were also employed to modify the nanostructures of the photoanodes, aiming to reduce the recombination and improve the transport of the photo-excited carriers at the interface 10 . To extend the activity of a photoelectrode into the visible light region, various approaches were employed including doping TiO 2 with other impurities, using dye-sensitized solar cells (DSSCs), and very recently using the composite semiconductors such as QD s-sensitized solar cells (QDSCs) [11][12][13] .…”