Materials for Photovoltaics: State of Art and Recent Developments

Abstract

In recent years, photovoltaic cell technology has grown extraordinarily as a sustainable source of energy, as a consequence of the increasing concern over the impact of fossil fuel-based energy on global warming and climate change. The different photovoltaic cells developed up to date can be classified into four main categories called generations (GEN), and the current market is mainly covered by the first two GEN. The 1GEN (mono or polycrystalline silicon cells and gallium arsenide) comprises well-known medium/low cost technologies that lead to moderate yields. The 2GEN (thin-film technologies) includes devices that have lower efficiency albeit are cheaper to manufacture. The 3GEN presents the use of novel materials, as well as a great variability of designs, and comprises expensive but very efficient cells. The 4GEN, also known as “inorganics-in-organics”, combines the low cost/flexibility of polymer thin films with the stability of novel inorganic nanostructures (i.e., metal nanoparticles and metal oxides) with organic-based nanomaterials (i.e., carbon nanotubes, graphene and its derivatives), and are currently under investigation. The main goal of this review is to show the current state of art on photovoltaic cell technology in terms of the materials used for the manufacture, efficiency and production costs. A comprehensive comparative analysis of the four generations is performed, including the device architectures, their advantages and limitations. Special emphasis is placed on the 4GEN, where the diverse roles of the organic and nano-components are discussed. Finally, conclusions and future perspectives are summarized.

Carbon-based materials for stable, cheaper and large-scale processable perovskite solar cells

“…The dispersion of graphene layers from graphite requires a large amount of organic solvents, such as dimethylformamide; on the other hand, the epitaxial growth on SiC by vacuum graphitization has the disadvantages of high temperature (1300 1C) and high costs of the monocrystalline SiC sheet. 33,34 Chemical vapour deposition (CVD) is more applicable on a large scale, but has hardly any control on film thickness and requires expensive substrates (Ni, Cu, Pd, Pt). 35 CNTs are composed of graphitic layers rolled up to form a cylinder.…”

“…For this reason, in each tube, an elevated charge-transfer resistance is created. 34,36 The problem is partially solved by the use of multi-walled CNTs (MWCNTs), which consist of multiple CNTs stacked together.…”

Pyrocatechol violet sensitized Ho-TiO2/ZnO nanostructured material: as photoanode for dye sensitized solar cells

“…For DSSC record power conversion efficiency is 12% for small cells and for minimodules is about 9% [5]. The aim of all the generations of PV devices is to reduce the cost and yielding a more durable and stable device with a better efficiency [6][7][8]. There are four basic components of DSSC, photo anode, dye, electrolyte and counter electrode.…”

Thin CdTe Layers Deposited by a Chamberless Inline Process using MOCVD, Simulation and Experiment

“…The growth rate of thin-film Cadmium Telluride (CdTe) using metalorganic chemical vapour deposition (MOCVD) has been found to be sensitive to both substrate temperature and reactant partial pressures [1], presenting a complex transport and kinetic process. Among the various deposition techniques used for CdTe growth, MOCVD is a favourable method, allowing control of the microstructure and stoichiometry of the films [2][3][4]. MOCVD is an attractive method for depositing CdTe and another group II-VI compound semiconductor thin films [5,6].…”