Electrodes For Photovoltaic Cells Research Articles

Recent Advances in Graphene-Enabled Materials for Photovoltaic Applications: A Comprehensive Review.

Graphene's two-dimensional structural arrangement has sparked a revolutionary transformation in the domain of conductive transparent devices, presenting a unique opportunity in the renewable energy sector. This comprehensive Review critically evaluates the most recent advances in graphene production and its employment in solar cells, focusing on dye-sensitized, organic, and perovskite devices for bulk heterojunction (BHJ) designs. This comprehensive investigation discovered the following captivating results: graphene integration resulted in a notable 20.3% improvement in energy conversion rates in graphene-perovskite photovoltaic cells. In comparison, BHJ cells saw a laudable 10% boost. Notably, graphene's 2D internal architecture emerges as a protector for photovoltaic devices, guaranteeing long-term stability against various environmental challenges. It acts as a transportation facilitator and charge extractor to the electrodes in photovoltaic cells. Additionally, this Review investigates current research highlighting the role of graphene derivatives and their products in solar PV systems, illuminating the way forward. The study elaborates on the complexities, challenges, and promising prospects underlying the use of graphene, revealing its reflective implications for the future of solar photovoltaic applications.

Transparent Conductive Oxides. Part I. General Review of Structural, Electrical and Optical Properties of TCOs Related to the Growth Techniques, Materials and Dopants

This contribution, based on literature review, presents a general overview of properties and applications of transparent conductive oxides, TCO. The requested properties of TCO are a high conductivity associated to high transparency in a wide wavelength range. The relation between the techniques used for deposition or growing TCO and the possibility of their doping with appropriate dopant and concentration were discussed relatively to their applications and properties. Thus, we present in this part, the various possible techniques for growing TCO and discuss the effect of the temperature on the functional properties. This self-consistent presentation is also considered to introduce a better understanding of the expected requirements for TCO integrated as transparent electrodes in photovoltaic cells and modules. These developments of TCO for photovoltaic applications will be presented in a second publication.

Probing Carrier Transport in Layered Perovskites with Nonlinear Optical and Photocurrent Spectroscopies

Interest in layered perovskite quantum wells is motivated by their potential for use in optoelectronic devices. In these systems, the smallest and largest quantum wells are most concentrated near opposing electrodes in photovoltaic cells. Coincident gradients in the energy levels and quantum well concentrations promote the funneling of electronic excitations and charge carriers through space. In this Perspective, we describe the development of several nonlinear optical techniques designed to elucidate the relaxation processes induced by light absorption in layered perovskite systems. Transient absorption microscopy provides insight into carrier diffusion and two-body recombination processes, whereas two-dimensional action spectroscopies are used to correlate elementary relaxation mechanisms to practical metrics of photovoltaic device performance. Our experiments suggest that charge carrier funneling processes do not facilitate long-range transport due to trapping. Rather, the bulklike phases of the films absorb light and transport carriers without participation of the smallest quantum wells.

Transparent Conducting Oxides As Cathodes in Li-O2 batteries: A First Principles Computational Investigation

Li-O2batteries have traditionally used carbon based electrodes (graphite, buckypaper) as the cathode of choice due to its good electrical conductivity, stability against non-aqueous electrolytes like dimethoxyethane (DME) and ease of handling. But, the carbon cathode also leads to formation of carbonate by-products that increase overpotentials during charging leading to degradation of the cathode and reduction of cyclability. Recent investigations have focused on using metal-oxides like SnO2, TiO2 as viable cathodes-alternatives in Li-O2 systems. In this paper, we investigate transparent conducting oxides (TCOs) as cathodes with focus on the interface between the TCO surfaces and the discharge product, Li2O2, in the Li-O2battery using first principles computations. TCOs have found use as electrodes in photovoltaic cells and other semi-conductor applications due to their tunable conductivity via defects/doping, ease of synthesis of preferred surfaces and stability to environmental factors. These properties, along with their stability against ethers, make them a promising class of cathodes in Li-O2 battery. Using DFT computations and thermodynamic arguments, we predict the chemical and electrochemical stability of some of the well-known TCOs in a Li-O2 battery. Further, surface adsorption computations show that not all oxides promote formation of Li2O2 and different surfaces of same cathode material can behave differently. We also explore the role dopants can play in achieving a stable electrically conducting cathode that promotes discharge of Li2O2. We extend the analysis to suggest possible oxide chemistries that should be investigated as cathodes in Li-O2batteries.

High-throughput optimization of near-infrared-transparent Mo-doped In2O3 thin films with high conductivity by combined use of atmospheric-pressure mist chemical-vapor deposition and sputtering

Thin films of near-infrared (NIR)-transparent and highly conductive Mo-doped In2O3 (IMO) were prepared as transparent electrodes in thin-film photovoltaic cells and energy-efficient windows. The fabrication process was rapidly optimized by the combined use of atmospheric-pressure mist chemical-vapor deposition (mist-CVD) and sputtering. Mist-CVD was used to rapidly deposit IMO thin films with various Mo-dopant concentrations. We obtained highly conductive IMO thin films with transmittance above 70% in a wide wavelength range of 0.3–2.5μm when the Mo-dopant concentration was ~1at% and the Mo dopants had an oxidation state of +4. The IMO films with the optimum Mo-dopant concentration of ~1at% had low resistivities of (3–4)×10−4Ωcm resulting from high electron mobilities exceeding 80cm2V−1s−1and suppressed electron densities of (2–3)×10−4cm−3, which prevented the degradation of transparency in the NIR region. We applied these findings to the growth of IMO thin films by sputter deposition, which is readily extendable from laboratory scale to industrial scale. As a result, a high-performance IMO film was successfully obtained in only a few deposition runs. The optimized sputtered IMO film exhibited an extraordinarily high electron mobility of 93cm2V−1s−1 and relatively low electron density of 1.5×1020cm−3, leading to a plasma wavelength that was longer than 4μm. This optimized IMO film allowed passage of the full solar spectrum and exclusively reflected far-infrared light corresponding to thermal radiation at room temperature, allowing it to be used as transparent electrodes in photovoltaic cells and heat-reflective electrodes in energy-efficient electrochromic windows. We believe the combination of mist-CVD and sputtering can be extended to rapid optimization of other functional oxide systems.

Dependence of Ga-doped ZnO thin film properties on different sputtering process parameters: Substrate temperature, sputtering pressure and bias voltage

This paper reports on the effects of different sputtering deposition process parameters (substrate temperature, sputtering pressure and bias voltage) on the electrical, optical, structural and morphological properties of gallium-doped ZnO (ZnO:Ga) of ~1μm thick. These highly transparent and conductive films were deposited on glass surfaces by d.c. pulsed magnetron sputtering from a GZO (ZnO(95.5):Ga2O3(4.5)) ceramic target in an argon atmosphere. X-ray diffraction experiments show that all films have a hexagonal wurtzite structure with the [001] preferred crystallographic direction, and the morphology of the films (obtained from scanning electron microscope analysis) is sensitive to the process parameters. All ZnO:Ga films have an average transmittance above 80% in the visible region, and the lowest electrical resistivity of 3.03×10−4Ω·cm was achieved for the sample submitted to the lowest bias voltage (−40V), which corresponds to a carrier concentration and a carrier mobility of 6.99×1020cm−3 and 29.49cm2V−1s−1, respectively. A high substrate temperature, high sputtering pressure and low negative bias voltage (within the range of studied parameters) proved to be very promising on obtaining optimized ZnO:Ga films, ensuring suitable properties for application as transparent electrodes in photovoltaic cells.

CdS-sensitized TiO2 nanocorals: hydrothermal synthesis, characterization, application

Cadmium sulfide (CdS) nanoparticle-sensitized titanium oxide nanocorals (TNC) were synthesized using a two-step deposition process. The TiO(2) nanocorals were grown on the conducting glass substrates (FTO) using A hydrothermal process and CdS nanoparticles were loaded on TNC using successive ionic layer adsorption and reaction (SILAR) method. The TiO(2), CdS and TiO(2)-CdS samples were characterized by optical absorption, X-ray diffraction (XRD), FT-Raman, FT-IR, scanning electron microscopy (SEM) and contact angle. Further, their photoelectrochemical (PEC) performance was tested in NaOH, Na(2)S-NaOH-S and Na(2)S electrolytes, respectively. When CdS nanoparticles are coated on TNCs, the optical absorption is found to be enhanced and band edge is red-shifted towards visible region. The TiO(2)-CdS sample exhibits improved photoelectrochemical (PEC) performance with maximum short circuit current of (J(sc)) 1.04 mA cm(-2). After applying these TiO(2)-CdS electrodes in photovoltaic cells, the photocurrent was found to be enhanced by 2.7 and 32.5 times, as compared with those of bare CdS and TiO(2) nanocorals films electrodes respectively. Also, the power conversion efficiency of TiO(2)-CdS electrodes is 0.72%, which is enhanced by about 16 and 29 times for TiO(2), CdS samples.

Nanorods and Nanotubes for Solar Cells

Nanorods and nanotubes as photoactive materials as well as electrodes in photovoltaic cells have been launched a few years ago, and the literature in this field started to appear only recently. The first steps have shown both advantages and disadvantages of their application, and the main expectation associated with their effective charge transport has not been realized completely. This article aims to review both the first and the recent tendencies in the development and application of nanorod and nanotube materials in photovoltaic cells. Two basic techniques of synthesis of crystalline nanorod structures are described, the top-down and bottom-up approaches, respectively. Design and photovoltaic performance of solar cells based on various semiconductor nanorod materials, such as TiO2, ZnO, CdS, CdSe, CdTe, CuO, Si are presented and compared with respective solar cells based on semiconductor nanoparticles. Specific of synthesis and application of carbon nanotubes in photovoltaic devices is also reviewed.

TiO 2@CdS core–shell nanorods films: Fabrication and dramatically enhanced photoelectrochemical properties

In this paper, we prepared TiO 2@CdS core–shell nanorods films electrodes using a simple and low-cost chemical bath deposition method. The core–shell nanorods films electrodes were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and UV–vis spectrometry techniques. After applying these TiO 2@CdS core–shell nanorods electrodes in photovoltaic cells, we found that the photocurrent was dramatically enhanced, comparing with those of bare TiO 2 nanorods and CdS films electrodes. Moreover, TiO 2@CdS core–shell nanorods film electrode showed better cell performance than CdS nanoparticles deposited TiO 2 nanoparticles (P25) film electrode. A photocurrent of 1.31 mA/cm 2, a fill factor of 0.43, an open circuit photovoltage of 0.44 V, and a conversion efficiency of 0.8% were obtained under an illumination of 32 mW/cm 2, when the CdS nanoparticles deposited on TiO 2 nanorods film for about 20 min. The maximum quantum efficiency of 5.0% was obtained at an incident wavelength of 500 nm. We believe that TiO 2@CdS core–shell heterostructured nanorods are excellent candidates for studying some fundamental aspects on charge separation and transfer in the fields of photovoltaic cells and photocatalysis.