Furui Tan

Improved photovoltaic performance of silicon nanowire/organic hybrid solar cells by incorporating silver nanoparticles.

Silicon nanowire (SiNW) arrays show an excellent light-trapping characteristic and high mobility for carriers. Surface plasmon resonance of silver nanoparticles (AgNPs) can be used to increase light scattering and absorption in solar cells. We fabricated a new kind of SiNW/organic hybrid solar cell by introducing AgNPs. Reflection spectra confirm the improved light scattering of AgNP-decorated SiNW arrays. A double-junction tandem structure was designed to manufacture our hybrid cells. Both short-circuit current and external quantum efficiency measurements show an enhancement in optical absorption of organic layer, especially at lower wavelengths.

Optical properties and electrical bistability of CdS nanoparticles synthesized in dodecanethiol

We reported the synthesis of CdS semiconductor nanoparticles using a simple one-pot reaction by thermolysis of cadmium acetylacetonate in dodecanethiol. Optical measurements of the as-obtained CdS nanoparticles revealed that their optical properties were closely related to surface effects. Based upon the cocktail of poly(N-vinylcarbazole) (PVK) and CdS nanoparticles, a bistable device was fabricated by a simple solution processing technique. Such a device exhibited a remarkable electrical bistability, which was attributed to the electric field-assisted charge transfer between PVK and the CdS nanoparticles capped by dodecaethiol. The conduction mechanism changed from an injection-controlled current to a bulk-controlled one during switching from OFF-state to ON-state.

Efficient hybrid plasmonic polymer solar cells with Ag nanoparticle decorated TiO2 nanorods embedded in the active layer

A hybrid plasmonic polymer solar cell, in which plasmonic metallic nanostructures (such as Ag, Au, and Pt nanoparticles) are embedded in the active layer, has been under intense scrutiny recently because it provides a promising new approach to enhance the efficiency of the device. We propose a brand new hybrid plasmonic nanostructure, which combines a plasmonic metallic nanostructure and one-dimensional semiconductor nanocrystals, to enhance the photocurrent of the device through a strong localized electric field and an enhanced charge transport channel. We demonstrate that when Ag nanoparticle decorated TiO2 nanorods were introduced into the active layer of polymer-fullerene based bulk heterojunction solar cells, the photocurrent significantly increased to 14.15 mA cm(-2) from 6.51 mA cm(-2) without a decrease in the open voltage; thus, the energy conversion efficiency was dramatically enhanced to 4.87% from 2.57%.

Efficient perovskite solar cells based on low-temperature solution-processed (CH3NH3)PbI3 perovskite/CuInS2 planar heterojunctions

In this work, the solution-processed CH3NH3PbI3 perovskite/copper indium disulfide (CuInS2) planar heterojunction solar cells with Al2O3 as a scaffold were fabricated at a temperature as low as 250°C for the first time, in which the indium tin oxide (ITO)-coated glass instead of the fluorine-doped tin oxide (FTO)-coated glass was used as the light-incidence electrode and the solution-processed CuInS2 layer was prepared to replace the commonly used TiO2 layer in previously reported perovskite-based solar cells. The influence of the thickness of the as-prepared CuInS2 film on the performance of the ITO/CuInS2(n)/Al2O3/(CH3NH3)PbI3/Ag cells was investigated. The ITO/CuInS2(2)/Al2O3/(CH3NH3)PbI3/Ag cell showed the best performance and achieved power conversion efficiency up to 5.30%.

Core/shell-shaped CdSe/PbS nanotetrapods for efficient organic–inorganic hybrid solar cells

Core/shell-shaped CdSe/PbS nanotetrapod (NT), a novel nanostructure, has been synthesized and incorporated as an electron acceptor in organic–inorganic hybrid bulk-heterojunction (HBH) solar cells with poly(3-hexylthiophene) (P3HT) acting as an electron donor. The composite NT shows an homogeneous decoration of 4 nm PbS quantum dots on the CdSe NT surface, forming an inorganic heterojunction with a type-II band alignment. Compared to pure CdSe NT, the core/shell-shaped NT demonstrates an improved performance on splitting photogenerated exciton in P3HT. The charge reverse transfer (leakage or recombination) at the heterojunction interface is suppressed due to a potential barrier that is as high as 0.5 eV for CdSe/PbS NT. Furthermore, charge transport and collection are also enhanced through the spatially isolated charge channels of P3HT (for holes) and the CdSe core (for electrons). The efficient exciton dissociation and charge collection greatly contribute to the photovoltaic performance improvement. Compared with the P3HT:CdSe hybrid solar cell, a remarkable efficiency enhancement of 76% is achieved by incorporating the P3HT:CdSe/PbS hybrid with a donor–acceptor mass ratio of 1 : 6.

Nickel sulfide films with significantly enhanced electrochemical performance induced by self-assembly of 4-aminothiophenol and their application in dye-sensitized solar cells

Dye-sensitized solar cells (DSSC) are a promising solution to global energy and environmental problems because of they are clean, low-cost, have high efficiency, good durability, and easy fabrication. However, seeking a platinum (Pt)-free CE alternative with high electrocatalytic activity and low cost to enhance the efficiency of the DSSC still is a key issue. In this study, a novel composite film of 4-aminothiophenol/nickel sulfide (4-ATP/NiS) was prepared by a two-step chemical/electrochemical process and served as the CE for a DSSC. The surface morphology of the 4-ATP/NiS composite film was characterized by field emission scanning electron microscopy (FESEM) and showed a microporous structure. The electrochemical performance of the 4-ATP/NiS (here marked as NiS*) counter electrode (CE) was evaluated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and Tafel curves, which revealed that the NiS* CE possessed excellent electrocatalytic activity for the reduction reaction of triiodide to iodide and low charge transfer resistance at the interface between the electrolyte and CE, respectively. The DSSC assembled with the novel NiS* CE achieved an enhanced power conversion efficiency of 7.20% under the irradiation of 100 mW cm−2 as compared to that of the DSSC based on a Pt electrode. Thus, this concept and therefore a significant enhancement in power conversion efficiency can be applied to other DSSCs with Pt-free CEs such as polyaniline, poly (3,4-ethylenedioxythiophene), graphene and so on.

Semitransparent inverted polymer solar cells employing a sol-gel-derived TiO2 electron-selective layer on FTO and MoO3/Ag/MoO3 transparent electrode

We report a new semitransparent inverted polymer solar cell (PSC) with a structure of glass/FTO/nc-TiO2/P3HT:PCBM/MoO3/Ag/MoO3. Because high-temperature annealing which decreased the conductivity of indium tin oxide (ITO) must be handled in the process of preparation of nanocrystalline titanium oxide (nc-TiO2), we replace glass/ITO with a glass/fluorine-doped tin oxide (FTO) substrate to improve the device performance. The experimental results show that the replacing FTO substrate enhances light transmittance between 400 and 600 nm and does not change sheet resistance after annealing treatment. The dependence of device performances on resistivity, light transmittance, and thickness of the MoO3/Ag/MoO3 film was investigated. High power conversion efficiency (PCE) was achieved for FTO substrate inverted PSCs, which showed about 75% increase compared to our previously reported ITO substrate device at different thicknesses of the MoO3/Ag/MoO3 transparent electrode films illuminated from the FTO side (bottom side) and about 150% increase illuminated from the MoO3/Ag/MoO3 side (top side).

Cadmium selenide quantum dots solar cells featuring nickel sulfide/polyaniline as efficient counter electrode provide 4.15% efficiency

Nickel sulfide decorated polyaniline (NiS/PANI) co-deposition onto fluorine-doped tin oxide (FTO) substrate using an in situ electropolymerization route and served as the counter electrode (CE) for polysulfide electrolyte in cadmium selenide (CdSe) quantum dots sensitized solar cells (QDSSCs). The NiS/PANI CE provided great electrocatalytic activity and lower charge-transfer resistance compared to the platinum (Pt), NiS and PANI CEs under the same preparation conditions prepared using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and Tafel polarization plots characterization. It was because the photoanode was modified with a TiO2 dense layer and thioglycolic acid that the QDSSC exhibited an improved fill factor and short-circuit current density. Under optimum conditions, the QDSSC featuring a NiS/PANI counter electrode provided an enhanced power conversion efficiency of 4.15% under an illumination of 100 mW cm−2.

Hybrid morphology dependence of CdTe:CdSe bulk-heterojunction solar cells.

A nanocrystal thin-film solar cell operating on an exciton splitting pattern requires a highly efficient separation of electron-hole pairs and transportation of separated charges. A hybrid bulk-heterojunction (HBH) nanostructure providing a large contact area and interpenetrated charge channels is favorable to an inorganic nanocrystal solar cell with high performance. For this freshly appeared structure, here in this work, we have firstly explored the influence of hybrid morphology on the photovoltaic performance of CdTe:CdSe bulk-heterojunction solar cells with variation in CdSe nanoparticle morphology. Quantum dot (QD) or nanotetrapod (NT)-shaped CdSe nanocrystals have been employed together with CdTe NTs to construct different hybrid structures. The solar cells with the two different hybrid active layers show obvious difference in photovoltaic performance. The hybrid structure with densely packed and continuously interpenetrated two phases generates superior morphological and electrical properties for more efficient inorganic bulk-heterojunction solar cells, which could be readily realized in the NTs:QDs hybrid. This proved strategy is applicable and promising in designing other highly efficient inorganic hybrid solar cells.

Nanotetrapods: quantum dot hybrid for bulk heterojunction solar cells

Hybrid thin film solar cell based on all-inorganic nanoparticles is a new member in the family of photovoltaic devices. In this work, a novel and performance-efficient inorganic hybrid nanostructure with continuous charge transportation and collection channels is demonstrated by introducing CdTe nanotetropods (NTs) and CdSe quantum dots (QDs). Hybrid morphology is characterized, demonstrating an interpenetration and compacted contact of NTs and QDs. Electrical measurements show enhanced charge transfer at the hybrid bulk heterojunction interface of NTs and QDs after ligand exchange which accordingly improves the performance of solar cells. Photovoltaic and light response tests exhibit a combined optic-electric contribution from both CdTe NTs and CdSe QDs through a formation of interpercolation in morphology as well as a type II energy level distribution. The NT and QD hybrid bulk heterojunction is applicable and promising in other highly efficient photovoltaic materials such as PbS QDs.