Sb2S3-sensitized Solar Cells Research Articles

One-step in situ synthesis of antimony sulfide/reduced graphene oxide composite as an absorber layer with enhanced photocurrent performances for solar cells

Antimony sulfide/reduced graphene oxide (Sb2S3-rGO) composite was successfully deposited on titanium dioxide (TiO2) nanorod array via a novel one-step chemical bath deposition method. The heterostructures were characterized by structural, optical, and electrochemical measurements. The self-assembled combination of Sb2S3 and reduced graphene oxide (rGO) nanostructure in the nanoarchitecture indicated a promising synergistic effect for solar cells with a remarkable enhanced electrochemical performance. The average crystallite size of 27 and 30 nm was calculated for Sb2S3-rGO and Sb2S3, respectively, from XRD measurement, and the diameter of nanoparticles grown on rGO nanosheet was estimated about 50 nm from FESEM images. Moreover, the result of electrochemical impedance spectroscopy (EIS) indicated that the TiO2/Sb2S3-rGO bilayer interfacial resistance was approximately five times lower than that of TiO2/Sb2S3. Additionally, TiO2/Sb2S3-rGO exhibited a rapid and stable photocurrent density that was seven times greater compared to that of TiO2/Sb2S3. These enhancements were mainly ascribed to the presence of the conductive rGO sheets that acting as an electron reservoir through retarding electron-hole recombination. These achievements strongly suggested the Sb2S3-rGO composite as a promising material for use as an absorber layer in solid state Sb2S3-sensitized solar cells.

Enhanced photovoltaic performance of Sb2S3-sensitized solar cell using a novel Ni-4 mercaptophenol hybrid interfacial layer

In this work, we introduced a novel Ni-4 mercaptophenol (Ni4MP) as an interfacial layer in Sb2S3-sensitized mesoporous TiO2 solar cells. Ni4MP thin films with controllable thickness were prepared by an integrated approach via atomic/molecular layer deposition techniques and were systematically characterized. Introduction of the Ni4MP interlayer significantly enhanced the photovoltaic performance and the interfacial charge transfer kinetics of Sb2S3-sensitized solar cells. The augmentation of open circuit voltage and short circuit density due to the insertion of a Ni4MP interlayer enhanced the power conversion efficiency of the solar cells from 2.07% to 2.79%, corresponding to a 35% increase in efficiency. This improvement in device performance was discussed based on the energy band diagram. We found that the Ni4MP interlayer can effectively extract the photogenerated holes from the Sb2S3 sensitizer due to the excellent band matching and hole scavenging characteristics, thus enhancing the charge transport and suppressing the recombination.

Template deposition of Sb2S3 for solid-state sensitized solar cells

Unavoidable impurities form in Sb2S3 absorber fabricated by conventional chemical bath deposition method which is harmful to the photovoltaic performance of Sb2S3-sensitized solar cells. To obtain high quality Sb2S3 absorber, a two-step template method is introduced to deposit Sb2S3 on mesoporous TiO2 film. This template method is performed by dipping ZnS-coated TiO2 films in a Sb source solution for several minutes. This low temperature method with short operation time allows large area deposition of Sb2S3. Properties of ZnS and Sb2S3 are systematically studied. X-ray photoelectron spectroscopy confirms the absence of impurities. The optimized Sb2S3 device exhibits a power conversion efficiency (PCE) of 3.69%, with an open-circuit voltage of 0.514 V, a short-circuit current-density of 12.14 mA/cm2, and a fill factor of 59.1% under AM 1.5G illumination which is better than the device fabricated by chemical bath deposition. The PCE of our Sb2S3 devices showed an obvious increase after 1–2 months storage which may be caused by reconstruction of the ZnS/Sb2S3 coating fabricated by partial cation exchange.

Key Factors Affecting the Performance of Sb2S3-sensitized Solar Cells During an Sb2S3 Deposition via SbCl3-thiourea Complex Solution-processing.

Sb2S3 is considered as one of the emerging light absorbers that can be applied to next-generation solar cells because of its unique optical and electrical properties. Recently, we demonstrated its potential as next-generation solar cells by achieving a high photovoltaic efficiency of > 6% in Sb2S3-sensitized solar cells using a simple thiourea (TU)-based complex solution method. Here, we describe the key experimental procedures for the deposition of Sb2S3 on a mesoporous TiO2 (mp-TiO2) layer using a SbCl3-TU complex solution in the fabrication of solar cells. First, the SbCl3-TU solution is synthesized by dissolving SbCl3 and TU in N,N-dimethylformamide at different molar ratios of SbCl3:TU. Then, the solution is deposited on as-prepared substrates consisting of mp-TiO2/TiO2-blocking layer/F-doped SnO2 glass by spin coating. Finally, to form crystalline Sb2S3, the samples are annealed in an N2-filled glove box at 300 °C. The effects of the experimental parameters on the photovoltaic device performance are also discussed.

Enhanced photovoltaic performance of Sb2S3-sensitized solar cells through surface treatments

Efficient antimony sulfide (Sb2S3)-sensitized solar cells were obtained by a sequential treatment with thioacetamide (TA) and 1-decylphosphonic acid (DPA). Compared with the untreated Sb2S3-sensitized solar cells, the power conversion efficiency of the treated Sb2S3 solar cells was improved by 1.80% to 3.23%. The TA treatment improved the Sb2S3 films by reducing impurities and decreasing the film’s surface defects, which inhibited the emergence of recombination centers. The DPA treatment reduced the recombination between hole transport materials (HTMs) and the Sb2S3. Therefore, we have presented an efficient strategy to improve the performance of Sb2S3-sensitized solar cells.

Improvement of nonlinear response for the power conversion efficiency with light intensities in cobalt complex electrolyte system

A vertically aligned TiO2 photoelectrode with sufficient space between TiO2 nanorods was synthesized by sacrificial templating of ZnO nanorods grown on a dense TiO2 layer/FTO film. The more expanded pore space in the TiO2 nanorod film than conventional mesoscopic TiO2 film greatly reduces the mass transport problem of cobalt electrolyte in the vicinity of the Sb2S3 sensitizer in Sb2S3-sensitized photoelectrochemical solar cells. Therefore, the nonlinearity of the power conversion efficiency (PCE) under illumination intensity was greatly relieved to 5.0% (0.1sun), 4.7% (0.5sun), and 3.7% (1sun) in a TiO2-nanorod-based Sb2S3-sensitized solar cell, whereas the efficiency of a mesoscopic-TiO2-based solar cell was significantly degraded to 5.3% (0.1 sun), 3.8% (0.5sun), and 2.3% (1sun).

A chemical precursor for depositing Sb2S3 onto mesoporous TiO2 layers in nonaqueous media and its application to solar cells

Deposition of nanocrystalline Sb(2)S(3) onto a mesoporous TiO(2) photoanode is an important process in the fabrication of Sb(2)S(3)-sensitized solar cells. In order to generate oxide-free nanosized Sb(2)S(3), a single-source precursor for the chemical bath deposition of Sb(2)S(3) in nonaqueous media, Sb(III)(thioacetamide)(2)Cl(3), was synthesized and used to produce high-quality Sb(2)S(3) for solar cells.

Toward Interaction of Sensitizer and Functional Moieties in Hole-Transporting Materials for Efficient Semiconductor-Sensitized Solar Cells

Sb(2)S(3)-sensitized mesoporous-TiO(2) solar cells using several conjugated polymers as hole-transporting materials (HTMs) are fabricated. We found that the cell performance was strongly correlated with the chemical interaction at the interface of Sb(2)S(3) as sensitizer and the HTMs through the thiophene moieties, which led to a higher fill factor (FF), open-circuit voltage (V(oc)), and short-circuit current density (J(sc)). With the application of PCPDTBT (poly(2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b']dithiophene)-alt-4,7(2,1,3-benzothiadiazole)) as a HTM in a Sb(2)S(3)-sensitized solar cell, overall power conversion efficiencies of 6.18, 6.57, and 6.53% at 100, 50, and 10% solar irradiation, respectively, were achieved with a metal mask.