Tin Sulfide (SnS) Films Deposited by an Electric Field-Assisted Continuous Spray Pyrolysis Technique with Application as Counter Electrodes in Dye-Sensitized Solar Cells

The deposition of tin sulfide (SnS) nanostructured films using a continuous spray pyrolysis technique is reported with an electric field present at the nozzle for influencing the atomization and the subsequent film deposition. In the absence of the electric field, the X-ray diffraction pattern shows the orthorhombic phase of SnS with a crystallographic preferred orientation along the (040) plane. The application of the electric field results in significant improvement in the morphology and a reduction in surface roughness (28 nm from 37 nm). The direct optical band gap of the films deposited with and without the electric field is estimated to be 1.5 and 1.7 eV, respectively. The photothermal deflection spectroscopy studies show a lower energetic disorder (no Urbach tail), which indicates an annealing effect in the SnS films deposited under the electric field. The improvement in the film properties is reflected in the expected improvement in the power conversion efficiency (PCE) of dye-sensitized solar cells fabricated using the SnS film as a counter electrode. An enhancement of PCE from 2.07% for the film deposited without the electric field to 2.89% for the film deposited with the electric field shows the role of the electric field in the fabrication of improved SnS film

Thermodynamic rating of an energy efficient chiller cum heater for metal hydride storage in hybrid photovoltaic - fuel cell (PVFC) system

Papers presented to the 11th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 20-23 July 2015.With dwindling energy resources which earth is having in the form of fossil fuels, today there is a scrupulous requirement of venturing alternative avenues, which can eventually share the ever-increasing energy demand. Solar photovoltaic is a reliable and clean source of energy. However due to its intermittent nature, it is vital to integrate solar photovoltaic with other sources of energy. Fuel cell technology because of its inherent environment friendly behavior has been an option that can fulfill this requirement. Present study deals with exploring the design challenges of integrating hydrogen fuel cell with solar photovoltaic. The continuous supply of hydrogen as fuel can be met in a safer and reliable manner through solid state storage of metal hydride system, with the hydrogen generated through an electrolyzer utilizing the PV (Photovoltaic) electricity. The challenges lie in dealing with the high-end exothermic reaction that occurs in the process of storing hydrogen in the metal hydride and the endothermic reaction that occurs in the process of extracting hydrogen. Therefore designing of an adequate cooling and heating arrangement for metal hydride storage system is also very important from efficient energy utilization point of view. Thermodynamic analysis of this cooling and heating circuit is reported for making an energy efficient PV/FC (Photovoltaic-fuel cell) system. The metal hydride unit is thermodynamically analyzed to critically ascertain the performance of the chiller that extracts the exothermic heat generation of the hydrides for the hydrogen storage to occur and the heater to achieve the reverse action. Several candidate approaches ranging from a simple back of the envelope calculations to sophisticated conjugate heat transfer analysis using CFD (Computational Fluid Dynamics) techniques are utilized to analyze the system. For the range of parameters considered, the study estimated the chiller and heater requirements of 250 W and 500 W respectively.Ms. Bharathy of GAIL has been extremely supportive of the work being done in IIT Delhi. Ms. Ashwini Mudgal has contributed for developing experimental setup of PV/FC hybrid system.Gas Authority of India Ltd. (GAIL) has funded the project on PV/FC Hybrid System.am201

Realization of Highly Efficient Polymer Solar Cell Based on PBDTTT-EFT and [71]PCBM

In this work, we have fabricated highly efficient polymer solar cells based on the blend of PBDTTT-EFT:PC71BM in the inverted device configuration. By using low temperature processed zinc oxide (ZnO) nanoparticles as an electron-transport layer (ETL) and 1,8-diiodooctane (DIO) as additive in chlorobenzene (CB) solvent we have achieved PCE of 9.43% with an excellent short-circuit current density (J(sc)) of 17.6 mAcm(-2), open circuit voltage (V-oc) of 0.80 V and fill factor (FF) of 0.67. These results reveals that addition of 3% DIO additive in CB solvent improve the morphology (lower charge carrier recombination and better metal/organic semiconductor interface) and provide uniform interpenetrating networks in PBDTTT-EFT:PC71BM blend active layer

Dye sensitized solar cells using the electric field assisted spray deposited kesterite (Cu2ZnSnS4) films as the counter electrodes for improved performance

Kesterite (Cu2ZnSnS4) thin films are spray deposited under 0 V and 1500 V DC voltages and then treated with N-2+H2S(5%) environment at 500 degrees C for 1 h for sulphurisation. The improvement in different properties like structural, optical, morphological and electrical occur in the kesterite films deposited under the electric field. The activation energy is also reduced for these films, after applying the DC voltage during the spray deposition. These improvements resulted in the enhancement of the catalytic properties of kesterite films for use as the counter electrodes in dye sensitized solar cells. Dye sensitized solar cell using the kesterite film as a counter electrode deposit under the applied voltage of 1500 V exhibits the power conversion efficiency of 4.93%, which is higher than that for the kesterite film deposit under the applied voltage = 0 V ( 3.77%). The power conversion efficiency of sulphurised kesterite films deposit at 0 V and 1500 V yield further improvement in the power conversion efficiency (6.58 and 7.67%, respectively)

Forster resonance energy transfer in organic photovoltaics devices fabricated by electric field assisted spray technique

Thin films of the ternary polymer blend (donors PCE-10 and PCDTBT with the acceptor PC71BM in chlombenzene) were fabricated by using spray coating technique without and with applied voltage to the nozzle during deposition. The increased absorption range from 400 nm to 800 nm indicates that Forster resonance energy transfer (FRET) is occurring for the films deposited under the electric field. This is also supported by photo-luminescence measurements and suggesting that under the applied voltage the orientation of polymer chains are changing at desired distances to facilitate FRET phenomenon to occur due to repulsion between uniformly charged ultrafine droplets. The size of droplets further reduced at higher applied voltage. Absorption, photo-luminescence, femtosecond transient absorption spectra and Kinetics traces were recorded to elucidate the role of applied DC voltages during the deposition of these films on photovoltaic performance of bulk heterojunction organic solar cell. The effect of FRET in polymer-polymer thin film under applied voltage during the deposition is observed, which indicates enhancement in the power conversion efficiency with the maximum value of 6.86% (J(sc) of 15.81 mA/cm(2) and V-oc of 0.77 V) at an applied voltage of 750 V

Tin Sulfide (SnS) Films Deposited by an Electric Field-Assisted Continuous Spray Pyrolysis Technique with Application as Counter Electrodes in Dye-Sensitized Solar Cells.

The deposition of tin sulfide (SnS) nanostructured films using a continuous spray pyrolysis technique is reported with an electric field present at the nozzle for influencing the atomization and the subsequent film deposition. In the absence of the electric field, the X-ray diffraction pattern shows the orthorhombic phase of SnS with a crystallographic preferred orientation along the (040) plane. The application of the electric field results in significant improvement in the morphology and a reduction in surface roughness (28 nm from 37 nm). The direct optical band gap of the films deposited with and without the electric field is estimated to be 1.5 and 1.7 eV, respectively. The photothermal deflection spectroscopy studies show a lower energetic disorder (no Urbach tail), which indicates an annealing effect in the SnS films deposited under the electric field. The improvement in the film properties is reflected in the expected improvement in the power conversion efficiency (PCE) of dye-sensitized solar cells fabricated using the SnS film as a counter electrode. An enhancement of PCE from 2.07% for the film deposited without the electric field to 2.89% for the film deposited with the electric field shows the role of the electric field in the fabrication of improved SnS films

CoSP approach for the synthesis of blue MoO3 nanoparticles for application as hole transport layer (HTL) in organic solar cells

The synthesis of MoO3 nanoparticles is reported using a Continuous Spray. Pyrolysis (CoSP) reactor and the influence of zone temperature, precursor concentration on the structural and morphological properties is investigated. The collected nanoparticles are utilized to prepare thin films by spin coating and further annealing at various temperatures. The improvement in morphology, crystallinity and the band gap shift shows the effectiveness of the annealing treatment in creating a proper hole transport layer for device applications. The technique thus allows the film formation using a non-vacuum method well suited for organic solar cells. The CoSP based MoO3 (CoSP_MoO3) films are demonstrated to have equal performance to hole-injection layers composed of thermally evaporated MoO3 (eMoO(3))

Enhancement of dye sensitized solar cell efficiency via incorporation of upconverting phosphor nanoparticles as spectral converters

Upconverting NaYF4:Yb3+,Er3+/NaYF4 core-shell (CS) nanoparticles (NPs) were synthesized by thermal decomposition of lanthanide trifluoroacetate precursors and mixed with TiO2 NPs to fabricate dye-sensitized solar cells (DSSCs). The CS geometry effectively prevents the capture of electrons because of the surface states and improves photo-emission. The as-synthesized CS NPs show upconversion (UC) luminescence, converting near infrared (NIR) light into visible light (450-700nm), making the photon absorption by the ruthenium-based dyes (which have little or no absorption in the NIR region) possible. The champion DSSCs fabricated using CS UC NPs (average size=25nm) show enhancements of similar to 12.5% (sensitized with black/N749 dye) and of similar to 5.5% (sensitized with N719 dye) in overall power conversion efficiency under AM 1.5G illumination. This variation in the enhancement of the DSSC efficiencies for black and N719 dyes is attributed to the difference in the extinction coefficient and the absorption wavelength range of dyes. Incident photon-to-current conversion efficiency measurements also evidently showed the photocurrent enhancement in the NIR region of the spectrum because of the UC effect. The results prove that the augmentation in efficiency is primarily due to NIR to visible spectrum modification by the fluorescent UC NPs