Ternary CuBiS2 nanoparticles as a sensitizer for quantum dot solar cells

Ternary Ag3AuS2 Nanocrystals for Thin-Film Solar Cells

The concept of clean and pollution-free energy development has promoted the rise of environmentally friendly silver-based chalcogenide nanocrystal (NC) solar cells, but currently reported silver-based NCs need complex synthesis processes at high temperatures that may bring zerovalent noble metal impurities for their high redox potentials. In this study, we report a facile synthesis of novel Ag3AuS2 NCs by injecting highly active oleylamine sulfur complexes as sulfur sources into metal precursor solutions at low temperatures of 60 °C. The obtained Ag3AuS2 NCs exhibit broad absorption spectra and high molar extinction coefficients (106 M-1 cm-1). Then, the Ag3AuS2 NCs are applied as the light-absorbing active layer in environmentally friendly thin-film solar cells. By introducing a hybrid mixture of charge acceptors and donors (NCs/P3HT hybrid film) at the interface, the device gains an absorption increment and enhanced charge extraction, achieving a final power conversion efficiency of 3.38%. This work demonstrates the enormous potential of Ag3AuS2 NCs from low-temperature preparation for photovoltaic applications.

CuGeO3 Nanoparticles: An Efficient Photothermal Theragnosis Agent for CT Imaging-Guided Photothermal Therapy of Cancers

The photothermal agents have been widely developed due to the minimally invasive treatment for targeted tumor photothermal therapy, which is considered to have great potential for antitumor bioapplications. The development of multifunctional photothermal agents is extremely challenging. This work presents a novel photothermal theragnosis agent, i.e., CuGeO3 nanoparticles (CGO NPs), showing intense absorption in the near-infrared (NIR) window and excellent ability of CT imaging. Due to the strong NIR absorption, CGO NPs exhibit excellent photothermal effect with a photothermal conversion efficiency of 59.4%. Moreover, because of the high X-ray attenuation coefficient of germanium, the CGO NPs have a great potential of CT imaging diagnosis in clinical application. Additionally, the CGO NPs show negligible cytotoxicity in vitro and in vivo, indicating that it can be served as an outstanding contrast and anticancer agent in a biosafe way. Our work opens the way for the development of bimetallic copper-based oxides used in photothermal diagnostic agents for cancer treatment.

Bandgap Tunable Ternary Cd x Sb2-y S3-δ Nanocrystals for Solar Cell Applications

We report the synthesis and photovoltaic performance of a new nonstoichiometric ternary metal sulfide alloyed semiconductor-Cd _x Sb_2-y S_3-δ nanocrystals prepared by the two-stage sequential ionic layer adsorption reaction technique. The synthesized Cd _x Sb_2-y S_3-δ nanocrystals retain the orthorhombic structure of the host Sb₂S₃ with Cd substituting a fraction (x = 0-0.15) of the cationic element Sb. The Cd _x Sb_2-y S_3-δ lattice expands relative to the host, Sb₂S_3, with its lattice constant a increasing linearly with Cd content x. Optical and external quantum efficiency (EQE) spectra revealed that the bandgap E _g of Cd _x Sb_2-y S_3-δ decreased from 1.99 to 1.69 eV (i.e., 625-737 nm) as x increased from 0 to 0.15. Liquid-junction Cd _x Sb_2-y S_3-δ quantum dot-sensitized solar cells were fabricated using the polyiodide electrolyte. The best cell yielded a power conversion efficiency (PCE) of 3.72% with the photovoltaic parameters of J _sc = 15.97 mA/cm², V _oc = 0.50 V, and FF = 46.6% under 1 sun. The PCE further increased to 4.86%, a respectable value for a new solar material, under a reduced light intensity of 10% sun. The PCE (4.86%) and J _sc (15.97 mA/cm²) are significantly larger than that (PCE = 1.8%, J _sc = 8.55 mA/cm²) of the Sb₂S₃ host. Electrochemical impedance spectroscopy showed that the ZnSe passivation coating increased the electron lifetime by three times. The EQE spectrum of Cd _x Sb_2-y S_3-δ has a maximal EQE of 82% at λ = 350 nm and covers the spectral range of 300-750 nm, which is significantly broader than that (300-625 nm) of the Sb₂S₃ host. The EQE-integrated current density yields a J _ph of 11.76 mA/cm². The tunable bandgap and a respectable PCE near 5% suggest that Cd _x Sb_2-y S_3-δ could be a potential candidate for a solar material.

Influence of a bifunctional linker on the loading of Cu2AgInS4 QDs onto porous TiO2 NFs to use as an efficient photoanode to boost the photoconversion efficiency of QDSCs

Quaternary Cu₂AgInS₄ quantum dots anchored more onto porous TiO₂ NFs through a linker, 3-mercaptopropionic acid exhibits higher photoconversion efficiency of QDSC than that of the same anchored without a linker.

SILAR controlled CdSe nanoparticles sensitized ZnO nanorods photoanode for solar cell application: Electrolyte effect

Controlled growth of different sizes of cadmium selenide (CdSe) nanoparticles over well aligned ZnO nanorods have been performed using successive ionic layer adsorption and reaction (SILAR) technique at room temperature (27 °C) in order to form nano heterostructure solar cells. Deposition of compact layer of zinc oxide (ZnO) by SILAR technique on fluorine doped tin oxide (FTO) coated glass substrate followed by growth of vertically aligned ZnO nanorods array using chemical bath deposition (CBD) at low temperature (<100 °C). Different characterization techniques viz. X-ray diffractometer, UV-Vis spectrophotometer, field emission scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy have been used to know the structural, optical, morphological and compositional properties of synthesized nano heterostructure. The photovoltaic performance of the cells with variation in SILAR cycles for CdSe and with use of different electrolytes have been recorded as J-V characteristics and the maximum conversion efficiency of 0.63% have been attained with ferro/ferri cyanide electrolyte for 12 cycles CdSe coating over 1-D ZnO nanorods.

Copper—antimony and copper—bismuth chalcogenides—Research opportunities and review for solar photovoltaics

The ternary Cu-Sb- and Cu-Bi-chalcogenides present a rich range of compounds of potential use for large-scale photovoltaics from Earth abundant elements. This paper reviews the state of fundamental knowledge about them, and their technological status with regard to solar cells. Research targets and missing data are highlighted, which may provide opportunities to help realize the goal of sustainable photovoltaics.

The family of ternary Cu-Sb- and Cu-Bi-chalcogenides and their solid solutions present a rich selection of potential candidates for Earth-abundant low toxicity photovoltaic (PV) absorber materials. Moreover, they have some novel features imparted by the ns2 lone pair of electrons on the Sb and Bi ions. This review evaluates them as electronic materials, including experimental and theoretical evaluations of their phases, thermodynamic stability, point defects, conductivity, optical data, and PV performances. Formation of the materials in bulk, thin film, and nanoforms and the properties of the materials are critically assessed with relevance to their suitability for PV devices. There is special emphasis on CuSbS2 and CuSbSe2 which form the mainstay of the device literature and provide the most insights into the present-day limitation of the device efficiencies to 3 or 4%. Missing features of the literature are highlighted and clear statements recommending potential research pathways are made, which may help advance the technological performance from its present stuck position.

Phase-Controlled Synthesis of High-Bi-Ratio Ternary Sulfide Nanocrystals of Cu1.57 Bi4.57 S8 and Cu2.93 Bi4.89 S9

High Bi-ratio ternary sulfides have been recently reported as superior thermoelectric materials. However, the synthesis of high Bi-ratio Cu-Bi-S nanocrystal remains a challenge. Reported here are the synthesis and characterization of three-phase Cu-Bi-S nanocrystals with the nominal chemical formulae of Cu_1.57 Bi_4.57 S₈ , Cu_2.93 Bi_4.89 S₉ and Cu₃ BiS₃ . The samples were prepared using a Bi₂ S₃ precursor by varying the amount and type of Cu_2-x S (i. e. Cu₂ S or Cu_7.2 S₄ ) reactants. TEM images reveal that two new samples crystalized having nanorod morphology with radii of approximately 50 nm and lengths of 200 nm. XPS results indicate that the valence states of Bi in both the two new phases are +3 with viable oxidation states for Cu. UV-Vis-NIR absorption spectroscopy reveals that narrow direct bandgaps are 1.12 and 1.27 eV for Cu_1.57 Bi_4.57 S₈ and Cu_2.93 Bi_4.89 S₉ , respectively. Besides, this method could also be applied to synthesize the Cu₃ BiS₃ phase with a new nanoplate morphology. The as-synthesized Cu-Bi-S samples show Cu/Bi ratio-dependent photoresponsive properties. This study not only reports the structure and bandgap of two ternary sulfides, which have only been discovered in the mineral previously, but also provides an efficient method for synthesizing Bi-rich ternary chalcogenide nanocrystals.

Solar light harvesting with multinary metal chalcogenide nanocrystals

The paper reviews the state of the art in the synthesis of multinary (ternary, quaternary and more complex) metal chalcogenide nanocrystals (NCs) and their applications as a light absorbing or an auxiliary component of light-harvesting systems. This includes solid-state and liquid-junction solar cells and photocatalytic/photoelectrochemical systems designed for the conversion of solar light into the electric current or the accumulation of solar energy in the form of products of various chemical reactions. The review discusses general aspects of the light absorption and photophysical properties of multinary metal chalcogenide NCs, the modern state of the synthetic strategies applied to produce the multinary metal chalcogenide NCs and related nanoheterostructures, and recent achievements in the metal chalcogenide NC-based solar cells and the photocatalytic/photoelectrochemical systems. The review is concluded by an outlook with a critical discussion of the most promising ways and challenging aspects of further progress in the metal chalcogenide NC-based solar photovoltaics and photochemistry.

Lead tin sulfide (Pb1-xSnxS) nanocrystals: A potential solar absorber material

We present a new ternary semiconductor absorber material - Pb_1-xSn_xS - for solar cells. Pb_1-xSn_xS nanocrystals (NCs) were synthesized using the successive ionic layer adsorption reaction (SILAR) process. Energy-dispersive X-ray spectroscopy revealed the Sn ratio for a sample prepared with five SILAR cycles to be x=0.55 (i.e. non-stoichiometric formula Pb_0.45Sn_0.55S). The optical spectra revealed that the energy gap E_g of the Pb_1-xSn_xS NCs decreased with an increasing number of SILAR cycles n, with E_g=1.67eV for the sample with n=5. Liquid-junction Pb_1-xSn_xS quantum dot-sensitized solar cells were fabricated using the polysulfide electrolyte. The best cell yielded a short-circuit current density J_sc of 10.1mA/cm², an open circuit voltage of 0.43V, a fill factor FF of 50% and an efficiency of 2.17% under 1 sun. The external quantum efficiency spectrum (EQE) covered a spectral range of 300-800nm with a maximum EQE of ∼67% at λ=650nm. At the reduced light of 0.1 sun, the efficiency increased to 3.31% (with a normalized J_sc=17.7mA/cm²) - a respectable efficiency for a new sensitizer. This work demonstrates that Pb_1-xSn_xS shows potential as a solar cell absorber.

Ion exchange-prepared NaSbSe2 nanocrystals: electronic structure and photovoltaic properties of a new solar absorber material

We report the calculated electronic structure, syntheses and photovoltaic properties of a new ternary solar absorber material NaSbSe₂.