Solid-state photoelectrochemical device based on poly(3-hexylthiophene) and an ion conducting polymer electrolyte, amorphous poly(ethylene oxide) complexed with I3/I redox couple

The photoelectrochemical properties of a solid-state photoelectrochemical cell (PEC) based on poly(3-hexylthiophene), P3HT, and an ion-conducting polymer electrolyte, amorphous poly(ethylene oxide), POMOE, complexed with I₃⁻/I⁻ redox couple has been constructed and studied. The current–voltage characteristics in the dark and under white light illumination, transient photocurrent and photovoltage studies, photocurrent action spectra for front and back side illuminations and an open-circuit voltage and short-circuit current dependence on light intensity have been studied. An open-circuit voltage of 130 mV and a short-circuit current of 0.47 μA cm⁻² were obtained at light intensity of 100 mW/cm². IPCE% of 0.024% for front side illumination (ITO/PEDOT) and IPCE% of 0.003% for backside illumination (ITO/P3HT) were obtained.     

Schottky solar cells with amorphous carbon nitride thin films prepared by ion beam sputtering technique

This paper reports on the successful deposition of amorphous carbon nitride thin films (a-CN_x) and fabrication of ITO/a-CN_x/Al Schottky thin-film solar cells by using the technique of ion beam sputtering. XPS and Raman spectra are used to characterize the deposited thin films. Nitrogen atoms are incorporated into the films in the form of carbon–nitrogen multiple bands. Their optical properties are also investigated using a spectroscopic ellipsometer and UV/VIS/NIR spectrophotometer. The refraction of the carbon nitride thin films deposited lies in the range of 1.7–2.1. The Tauc optical band gap is about 0.6 eV. The photovoltaic values of the device, short-circuit current and open-circuit voltage are 1.56 μA/cm² and 250 mV, respectively, when exposed to AM1.5 illumination (100 mW/cm², 25°C).     

P3HT/ZnO bulk-heterojunction solar cell sensitized by a perylene derivative

In this work, a soluble perylene-derivative dye, N, N′-didodecyl-3,4,9,10-perylene tetracarboxylic diimide (PDI), was used to improve the photovoltaic performance of poly(3-hexylthiophene) (P3HT)/ZnO bulk heterojunction cells through blending with the composite. Results show that by incorporation of PDI in the P3HT/ZnO composite, the light absorption and exciton separation can be significantly improved. The photocurrent under white-light irradiation can be increased from 6.35 to 9.55 mA/cm². Solar decay experiment shows that V_OC of the ITO/PEDOT:PSS/P3HT:ZnO:PDI/Al device decreases rapidly to almost zero in 1 h under persistent white-light illumination. After placing a 420 nm cutoff filter between the cell and the xenon lamp, the stability of the cell can be significantly improved. The device performance can maintain about 80% of the original value within 30 h and I_SC degraded to zero after 142 h. The addition of PDI into the P3HT/ZnO device up to 5 wt% does not show observable effect on the solar cell decay behavior.     

Photoelectrochemical studies of the junction between poly[3-(4-octylphenyl)thiophene] and a redox polymer electrolyte

The photoelectrochemical properties of all-solid-state photoelectrochemical cell constructed from a conjugated polymer poly[3-(4-octylphenyl)thiophene] and an amorphous poly(ethylene oxide) complexed with iodide/triiodide redox couple were studied. In order to develop flexible photoelectrochemical cells, we have used a transparent polymeric metal, doped poly(3,4-ethylenedioxythiophene), as a counter electrode. It was shown that poly(3,4-ethylenedioxythiophene) improved the charge transfer between indium tin-oxide and iodide/triiodide redox couple. The spectral response, photocurrent time, and open-circuit voltage and short-circuit current dependence on light intensity have been studied. The photon to electron conversion efficiency obtained was low. The photocurrent and photovoltage dependence studies on light intensity indicate exciton recombination and/or traps as limiting factors.     

Solid-state photoelectrochemical cell using a polythiophene derivative as photoactive electrode

In this work, we investigated the photoelectrochemical behavior of poly(4,4′-dipentoxy-2,2′-bithiophene), poly(ET2), as a single electrode in a liquid electrolyte and also its use in a solid-state photoelectrochemical device using a polymeric electrolyte. The results showed a strong dependence of the photocurrent density on the type and concentration of the redox couple. The solid-state device exhibited a short-circuit current density of 4 μA cm⁻² and an open-circuit voltage of 9 mV. The maximum quantum yield of photocurrent in the visible range was 0.17%, high when compared to other photoelectrochemical devices based on organic materials; however, it is low in comparison to solid-state devices using inorganic materials. This paper shows the viability of using organic polymeric electrolytes in the construction of photoelectrochemical devices.     

Novel hybrid polymer photovoltaics made by generating silver nanoparticles in polymer:fullerene bulk-heterojunction structures

Here, we developed the high efficient poly(3-hexylthiophene) (P3HT):[6,6]-phenyl C₆₁-butyric acid butyl ester (PCBB):Ag nanoparticle hybrid photovoltaic cells by generating the silver nanoparticles in the bulk-heterojunction structures of P3HT:PCBB prior to the spin-coating process. Hybrid bulk-heterojunction solar cells with an ITO/(G)-PEDOT/P3HT:PCBB:Ag/Al was fabricated, which shows open-circuit voltage, short-circuit current density, and power conversion efficiency of 0.639 V, 12.29 mA/cm², and 4.30% under AM1.5 irradiation (100 mW/cm²), respectively.     

Characterization of N, N′-bis-2-(1-hydoxy-4-methylpentyl)-3, 4, 9, 10-perylene bis (dicarboximide) sensitized nanocrystalline TiO2 solar cells with polythiophene hole conductors

We have fabricated solid-state, dye-sensitized nanocrystalline TiO₂ solar cells (DSSC) based on perylene derivative dye, N,N′-bis-2-(1-hydoxy-4-methylpentyl)-3,4,9,10-perylene bis (dicarboximide) (HMPER) with two different polythiophenes as hole conductors; i.e. poly (3-octyl thiophene) (P3OT) and poly (3-hexyl thiophene) (P3HT), respectively. HMPER adsorbs strongly to the surface of nanocrystalline TiO₂ and inject electrons into TiO₂ conduction band upon absorption of light. Polythiophene derivatives are well-known materials as hole conductors in solid-state dye-sensitized solar cells. We obtained quite similar results with P3OT and P3HT yielding a short-circuit current density of around 80 μA/cm² and open-circuit voltage of around 0.7 V at 80 mW/cm² AM 1.5 light intensity. The results are compared with Ru-535 TBA-sensitized nc-TiO₂ cells prepared by using the same polythiophene derivatives.     

加热和水处理共同调控PbI2薄膜形貌及其在钙钛矿太阳电池中的应用研究

该文研究加热和水处理共同作用对PbI₂薄膜形貌的调控和对钙钛矿太阳电池性能的影响。使用的钙钛矿体系为（FAPbI₃）_1-x（MAPbBr₃）_x,并在两步法工艺基础上对PbI₂薄膜进行不同时间加热和短时间水处理可将PbI₂薄膜制备成多孔结构。将双重处理后的PbI₂薄膜制备成钙钛矿薄膜后,可发现钙钛矿薄膜质量明显提升,表现在：钙钛矿的晶粒尺寸明显增大、结晶性增强、吸光能力提升、载流子传输更快。且此种方式能有效调控钙钛矿薄膜中的PbI₂残留量。在器件效率方面,只对PbI₂薄膜进行加热处理制备的电池的开路电压、短路电流、填充因子和效率分别为1.05 V、23.12 mA/cm²、73.81%和17.92%,而在最优双重处理工艺下制备的电池的这4个相应的参数分别为1.09 V、24.75 mA/cm²、77.85%和21.10%。     

Comparison of normal and inverse poly(3-hexylthiophene)/fullerene solar cell architectures

Polymer solar cells based on regioregular poly(3-hexylthiophene) (P3HT) and ([6,6]-phenyl-C61-butyric acid methyl ester) (PCBM) were fabricated with two different architectures (normal and inverse). Normal cells using indium tin oxide (ITO) as anode and Al as cathode were fabricated on polyester foils and illuminated from substrate side. Inverse cells using Ti as cathode and ultrathin Au layer as anode were illuminated from the top side covered by a transparent Au contact. Both Au layer and PET/ITO show comparable transmission in the spectral range where P3HT absorbs. Inverse cells showed comparable device parameters to normal cell (open circuit voltage 550 mV, short circuit current 6.25 mA/cm², fill factor 0.33 and white light power conversion efficiency 1.12%).     

Efficient hybrid carboxylated polythiophene/nanocrystalline TiO2 heterojunction solar cells

Efficient hybrid solar cells fabricated from TiO₂, novel carboxylated polythiophene poly (3-thiophenemalonic acid) P3TMA as sensitizer as well as hole conductor and poly (3-hexylthiophene) (P3HT) as hole transporter was described. UV-Vis absorption and morphology of the active layer were investigated. Device J/V characterizations with different P3HT layer thickness were measured and discussed. Efficiency improvements were observed in thinner P3HT layer thickness and with poly[3,4-(ethylenedioxy)-thiophene]:poly(styrene sulfonate) (PEDOT:PSS) as charge collection layer, and such device showed a short-circuit current density of 1.32 mA/cm², an open-circuit voltage of 0.44 V, a fill factor of 0.43, and a energy conversion efficiency of 0.25% at A.M. 1.5 solar illumination (100 mW/cm²).     

Effect of ionic conductivity of a PVC–LiClO4 based solid polymeric electrolyte on the performance of solar cells of ITO/TiO2/PVC–LiClO4/graphite

This paper reports the effect of ionic conductivity of the solid polymeric electrolyte of polyvinylchloride–lithium perchlorate (PVC–LiClO₄) on the performance of a solar cell of ITO/TiO₂/PVC–LiClO₄/graphite. Titanium dioxide films have been used as a photoelectrochemical solar cells. The films were deposited onto a ITO-coated glass substrate by a screen printing technique. The electrolytes were prepared by solution casting. The ionic conductivity of the electrolytes was obtained with an impedance spectroscopy technique. ITO and graphite films were chosen as the front and counter electrode of the device, respectively. The graphite films were deposited onto a glass substrate by the electron-beam evaporation technique. The short-circuit current density and open-circuit voltage of the device were found to increase with increasing ionic conductivity of solid polymeric electrolyte of PVC–LiClO_4. The highest short-circuit current density and open-circuit voltage were 0.94 μA cm⁻² and 186 mV, respectively. The conversion efficiency was low.     

Electrochemistry of poly(vinylferrocene) modified electrodes in aqueous acidic media

A cyclic voltammetric study of the electrochemistry and chemical stability of the poly(vinylferrocene) (PVFc) redox couple, coated on a gold substrate, in aqueous solutions of H₂SO₄, HClO₄ and HCl was carried out. It was found that the anodic peak potential (E_pa) did not depend on the acid concentration in the range (1.0 × 10⁻² to 1.0 × 10⁻⁷ mol L⁻¹). However, the E_pa values shifted linearly to less positive potentials when investigated in more concentrated acid solutions in the range 1–5 mol L⁻¹. The slope of the E_pa versus acid concentration graph was found to be in the order H₂SO₄ > HCl > HClO₄. In this regard PVFc behaved very similar to 1,1′-bis(11-mercaptoundecyl)ferrocene (Fc(C₁₁SH)₂) except for its chemical stability. In H₂SO₄ media the PVFc was found to be much less stable than 1,1′-Fc(C₁₁SH)₂. The dependence of E_pa on acid concentration could be used to monitor state of charge of lead-acid batteries. However, for this application Fc(C₁₁SH)₂ would be a better choice because of its superior chemical stability.     

Development of Cu(InGa)Se2-based thin-film PV modules with a Zn(O,S,OH)x buffer layer

The CBD-Zn(O,S,OH)_x buffer process is reviewed. Applying this buffer, our highest efficiencies are achieved, such as a circuit (or submodule) efficiency of 14.2% at an aperture area of 864 cm² on a 30 cm × 30 cm-sized substrate and module efficiencies of 13.4% at an aperture area of 3459 cm² on a mosaic module in which four 30 cm × 30 cm-sized circuits are connected in parallel and 12.8% at an aperture area of 3456 cm² on a 30 cm × 120 cm-sized substrate. Our module structure is a cover glass/EVA/MOCVD-BZO window/CBD-Zn(O,S,OH)_x buffer/CIGSS surface layer/CIGS absorber/Mo base electrode/soda-lime glass. Development of both the hardware (i.e. CBD apparatus) applicable to the mass production and the suitable control parameters is necessary to establish the robust baseline process for the CBD-Zn(O,S,OH)_x buffer. Finding of %T monitoring and post-deposition light soaking in this buffer process contributes not only to improve the reproducibility, but also to enhance the electrical yield and the I–V performance.     

Effect of non-graphitized carbon electrodes on the electrochemical characteristics of a thermocell with a Br2/Br redox couple

Electrodes made from a non-graphitized carbon (Maxsorb) sheet with a large specific surface area greatly improved the electrochemical characteristics of thermocells with a bromine/bromide-ion redox couple and a KBr aqueous electrolyte saturated with Br₂. The Maxsorb electrodes provide a higher open-circuit voltage than graphite (Perma Foil) electrodes and the maximum discharge current density is 2.4 mA/cm² until the voltage reaches 0 V. The Maxsorb electrodes generate 5.68 mV/°C of thermoelectric power at a temperature difference greater than 40°C, which is 2.5 times the power reported previously. The Maxsorb electrodes also improve the cathodic polarization in the presence of a gas-liquid-solid interface in Br₂-free electrolyte, while the graphite electrodes do not. Nevertheless, this improvement is insufficient to observe when the KBr electrolyte is saturated with Br₂. An experimental cell with Maxsorb electrodes maintains a stable voltage up to 2.0 mA/cm² for over 450 h, even though the cell configuration has still to be optimized.     

Sm0.5Sr0.5CoO3 + Sm0.2Ce0.8O1.9 composite cathode for cermet supported thin Sm0.2Ce0.8O1.9 electrolyte SOFC operating below 600 °C

The cathode is a key component in low temperature solid oxide fuel cells. In this study, composite cathode, 75 wt.% Sm_0.5Sr_0.5CoO₃ (SSC) + 25 wt.% Sm_0.2Ce_0.8O_1.9 (SDC), was applied on the cermet supported thin SDC electrolyte cell which was fabricated by tape casting, screen-printing, and co-firing. Single cells with the composite cathodes sintered at different temperatures were tested from 400 to 650 °C. The best cell performance, 0.75 W cm⁻² peak power operating at 600 °C, was obtained from the 1050 °C sintered cathode. The measured thin SDC electrolyte resistance R_s was 0.128 Ω cm² and total electrode polarization R_p(a + c) was only 0.102 Ω cm² at 600 °C.     

Singlet methylene removal by saturated and unsaturated hydrocarbons

The technique of laser flash phyotolysis/laser absorption has been used to obtain absolute removal rate constants for singlet methylene, ¹CH₂ (ã¹A₁), with various saturated and unsaturated hydrocarbons. The removal rate constants for CH₄, C₂H₆, C₃H₈, C₂H₄, C₃H₆, C₂H₂, CH₂CCH₂, and C₆H₆ were found to be in excellent agreement with previously reported results. Removal rate constants were also measured for n-C₄H₁₀, i-C₄H₁₀, n-C₅H₁₂, c-C₃H₆, c-C₆H₁₂, 1-C₄H₈, cis-2-C₄H₈, trans-2-C₄H₈, and 1-C₄H₆, and determined to be (3.17 ± 0.15), (2.53 ± 0.11), (3.35 ± 0.24), (1.63 ± 0.08), (3.77 ± 0.21), (3.80 ± 0.20), (3.67 ± 0.16), (3.43 ± 0.16) and (4.05 ± 0.18) × 10⁻¹⁰ cm³ molecule⁻¹ s⁻¹, respectively. This series of hydrocarbons forms the basis of a larger series of compounds containing a wide variety of organic functional groups. The removal rate constants are reported here, both as a series within its own right, and as a reference point for future work.     

Large area CIGS2 thin film solar cells on foils: nucleus of a pilot plant

In earlier research, conversion efficiency of 10.4% (AM1.5) and 9.9% (AM0) has been achieved on small area CuIn_xGa_1−xS₂ (CIGS2) solar cell on 127 μm thick stainless steel substrate. The area of research is mainly focused on studying CIGS2 thin films as solar cell absorber material and growing high efficiency cells on ultralightweight and flexible metallic foils such as 127 μm thick stainless steel and SiO₂ coated 25 μm thick Ti foils. This paper presents the scaling up process of CIGS2 thin film substrate from 2.5 × 2.5 cm² to 10 × 10 cm². Initial scaling up efforts focused on achieving uniform thickness and stress-free films. Process of scaling up consisted of refurbishment of selenization/sulfurization furnace, design and fabrication of scrubber and enlargement of new CdS deposition setup. The scaling up from 2.5 × 2.5 cm² to 10 × 10 cm² substrate size has laid the foundation for PV Materials Lab of Florida Solar Energy Center becoming the nucleus of a pilot plant.     

Organic heterojunction photovoltaic cells: role of functional groups in electron acceptor materials

We have fabricated and characterized some donor/acceptor type photovoltaic devices. While zinc phthalocyanine has been the donor material, a series of acceptor materials with identical backbone but different strength has been chosen. The role of function groups in acceptor material on photovoltaic device characteristics has been studied under different illumination intensities. Origin of the open-circuit voltage has been discussed considering ionization potential of donor and electron affinity of the acceptor material. Nonlinear increase of short-circuit current on light intensity has been observed and discussed in terms of conductance switching of acceptor material via electroreduction.     

Reduction of hydrogen peroxide production at anode of proton exchange membrane fuel cell under open-circuit conditions using ruthenium–carbon catalyst

This study examines the effect of hydrogen peroxide (H₂O₂) on the open-circuit voltage (OCV) of a proton exchange membrane fuel cell (PEMFC) and the reduction of H₂O₂ in the membrane using a ruthenium/carbon catalyst (Ru/C) at the anode. Each cathode and anode potential of the PEMFC in the presence of H₂O₂ is examined by constructing a half-cell using 1.0 M H₂SO₄ solution as an electrolyte and Ag/AgCl as the reference electrode. H₂O₂ is added to the H₂SO₄ solution and the half-cell potential is measured at each H₂O₂ concentration. The cathode potential is affected by the H₂O₂ concentration while the anode potential remains stable. A Ru catalyst is used to reduce the level of H₂O₂ formation through O₂ cross-over at the interface of a membrane and the anode. The Ru catalyst is known to produce less H₂O₂ through oxygen reduction at the anode of PEMFC than a Pt catalyst. A Ru/C layer is placed between the Nafion^® 112 membrane and anode catalyst layer and the cell voltage under open-circuit condition is measured. A single cell is constructed to compare the OCV of the Pt/C only anode with that of the Ru/C-layered anode. The level of hydrogen cross-over and the OCV are determined after operation at a current density of 1 A cm⁻² for 10 h and stabilization at open-circuit for 1 h to obtain an equilibrium state in the cell. Although there is an increase in the OCV of the cell with the Ru/C layer at the anode, excessive addition of Ru/C has an adverse effect on cell performance.     

Optimization of inverted tandem organic solar cells

Inverted tandem organic solar cells, consisting of two bulk heterojunction sub-cells with identical poly(3-hexylthiophene) (P3HT) and 1-(3-methoxycarbonyl)-propyl-1-phenyl-(6,6)C₆₁ (PCBM) active layer and a MoO₃/Ag/Al/Ca intermediate layer, have been presented and optimized. Indium tin oxide (ITO) modified by Ca acts as a cathode for electron collection and Ag is used as the anode for hole collection for the tandem device. A proper thickness of Ca (3 nm) forms a continuous layer, working as a cathode for the top sub-cell. MoO₃ as the anode buffer layer prevents exciton quenching and charge loss at the anode side, which could result in increase in interfacial resistance. The variance of sub-cell thickness adjusts the optical field distribution in the entire device, facilitating light absorption and good current matching in both sub-cells. The optimal inverted tandem device achieves a maximum power conversion efficiency of 2.89% with a short-circuit current density of 4.19 mA/cm², an open-circuit voltage of 1.17 V, and a fill factor of 59.0% under simulated 100 mW/cm² (AM 1.5G) solar irradiation.