Thin film solar cells (TFSC) are a promising approach for terrestrial and space photovoltaics and offer a wide variety of choices in terms of the device design and fabrication. A variety of substrates (flexible or rigid, metal or insulator) can be used for deposition of different layers (contact, buffer, absorber, reflector, etc.) using different techniques (PVD, CVD, ECD, plasma‐based, hybrid, etc.). Such versatility allows tailoring and engineering of the layers in order to improve device performance. For large‐area devices required for realistic applications, thin‐film device fabrication becomes complex and requires proper control over the entire process sequence. Proper understanding of thin‐film deposition processes can help in achieving high‐efficiency devices over large areas, as has been demonstrated commercially for different cells. Research and development in new, exotic and simple materials and devices, and innovative, but simple manufacturing processes need to be pursued in a focussed manner. Which cell(s) and which technologies will ultimately succeed commercially continue to be anybody's guess, but it would surely be determined by the simplicity of manufacturability and the cost per reliable watt. Cheap and moderately efficient TFSC are expected to receive a due commercial place under the sun. Copyright © 2004 John Wiley & Sons, Ltd.

Tin oxide films have been prepared on glass substrates by spray pyrolysis technique. The electrical and optical properties of undoped and antimony-doped tin oxide films have been studied. The temperature dependence of electron mobility has been analyzed to establish the electron conduction mechanism. Optical properties near the plasma edge have been analyzed using Drude’s theory. The dependence of effective mass on carrier concentration has been explained on the basis of nonparabolicity of the conduction band. The shift in the Fermi energy, calculated on the basis of energy dependent effective mass, is consistent with the measured shift in the absorption edge.

A comprehensive review of up-conversion (UP) and down-conversion (DC) or down shifting of rare earth (RE) doped zinc oxide (ZnO) nanophosphors is presented. Research interest in the development of RE 3+ doped ZnO for UP and DC nanophosphors has been encouraged by the potential application of these materials in light emitting diodes and different types of photovoltaic cells. A range of remarkable characteristics, which are organized into different sections describing the structure, optical, and luminescence properties of these materials, are discussed in detail. Undoped ZnO has two characteristic emissions in the ultraviolet and visible regions related, respectively, to excitonic recombination and intrinsic defects. X-ray photoelectron spectroscopy (XPS) data demonstrated a correlation between the visible emission and intrinsic defects. In the case of the DC or shifting process, there was simultaneous emissions related to f → f transitions of RE ions and defects in ZnO host. These emissions were dependent on the synthesis method, annealing temperature, and RE ion concentration, among other things; only f → f transitions of RE ions were observed in the case of the UC process. These down and up conversion RE doped ZnO phosphors were evaluated for a possible application in solid state lighting and photovoltaic cells.

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Electrical and optical properties of doped tin and zinc oxide thin films by atmospheric pressure chemical vapor deposition AIP Conf.Electrical and optical properties of undoped and antimonydoped tin oxide films

Silver nanoparticles of various sizes, shapes and modified distances between them were prepared on silicon substrates using thermally evaporated metal thin films of varying thicknesses followed by annealing. The ∼4 nm silver thin film annealed around ∼300 °C showed considerable reflectance reduction from the silicon substrate in the entire polychromatic spectrum. The effects of dipolar and quadrupolar resonances of silver nanoparticles on the reflectance reduction from the silicon substrate are discussed. The quadrupolar resonances of silver nanoparticles lead to reduced reflectance from the silicon substrate in the near UV–visible region (∼350–600 nm) due to the enhanced forward scattering. The reflectance reduction in the Vis and NIR regions (∼600–1300 nm range) is explained by the interaction of the surface plasmons of the metal nanoparticles, which is very sensitive to the size and shape of the particles, and the distances between them. Some of the waveguide modes existing at the interface between the silicon and the metal nanoparticles also couple the excited surface plasmons, which helps in trapping the light near the NIR region. With proper tuning of the metal particle sizes, shapes and distances between the particles in the layers, one can reduce the total reflectance from the silicon substrate in the entire polychromatic solar spectrum.

Mixed organic–inorganic halide perovskite solar cells have reached unprecedentedly high efficiency in a short term. Two major challenges in its large-scale deployment is the material instability and hazardous lead waste. Several studies have identified that lead replacement with its other alternatives does not show the similar assurance. In this manuscript, we introduce the concept of recycling of the degraded perovskite film (PbI 2 ), gaining back the initial optoelectronic properties as the best possible solution to avoid lead waste. The simple recycling procedure allows the utilization of some of the most expensive (fluorine-doped tin oxide), primary energy-consuming (TiO 2 ), and toxic (Pb) parts of the solar cell, reducing the payback time even further. This addresses the major issues of instability and expensive toxic lead disposal, altogether. We have demonstrated the comparative study of feasibility of recycling in degraded perovskite films deposited by three different standard fabrication routes. Films fabricated via acetate route shows efficient recycling compared to the other routes, i.e., chloride and sequential deposition routes. Moreover, recycling in sequentially deposited films needs further optimization.

Hydrophobic and surfactant-free ZnO nanoparticles and ZnO decorated graphene nanocomposite (Z@G) with narrow and uniform size distribution were synthesized by a time-efficient microwave-assisted hydrothermal reaction that can be used specifically for application in hybrid photovoltaics. The synthesized ZnO nanoparticles and Z@G nanocomposite showed stable and clear dispersion in chloroform and methanol (with volume ratio of 9 : 1) and chloroform and ethanol (volume ratio 9 : 1).Being hydrophobic, these inorganic samples blend very well with organic polymer solution in chlorobenzene, which is a prerequisite to cast smooth and undisrupted film for hybrid solar cell application. The introduction of these hydrophobic nanoparticles into PCPDTBT:PCBM-based bulkheterojunction polymer solar cells resulted in significant improvement in solar cell J-V characteristics with enhancement in open circuit voltage (V OC ), short circuit current density (J SC ) and thereby overall improvement in cell efficiency. With the optimization of the weight ratio of polymer, fullerene and synthesized ZnO nanoparticles/Z@G nanocomposite, the power conversion efficiencies 1.76% and 3.65% were achieved.