Part of the book: Application of Solar Energy
Non-traditional design of multi-layered solar energy converters is proposed, with electrically independent p-i-n junctions. This new approach allows utilization of cheap and abundant II-VI, IV and IV-VI materials instead of III-V ones, using also cheap and economic deposition techniques like Chemical Bath Deposition (CBD) or Chemical Vapor Deposition (CVD) instead of expensive Molecular Beam Epitaxy (MBE). The CVD reactor with three atomic sources was built and used. II-VI and IV-VI semiconductor materials were prepared either in CVD reactor, or by CBD techniques. Besides, the original two-stage technology was employed: first the precursor oxide/hydroxide film of corresponding metal (like cadmium oxide/hydroxide) was prepared by some variety of CBD methods, and at the second stage, in CVD reactor the non-metallic component of precursor film was substituted by chalcogen, producing materials like CdS, CdSe, PbTe, etc. The semiconductor materials thus produced were of high quality, with basic parameters corresponding to those for the single crystals. Several experimental multilayered converters were constructed (in particular, with CdS/CdTe, CdS/PbS and Si/PbTe active bilayers). The preliminary results of their studying have shown that these and similar devices can be used in solar cells and photo sensors with satisfactory efficiency, and have great potential for improvement.
Part of the book: Sustainable Energy
Luminescent silicon‐rich dielectric materials have been under intensive research due to their potential applications in optoelectronic devices. Silicon‐rich nitride (SRN) and silicon‐rich oxide (SRO) films have been mostly studied because of their high luminescence and compatibility with the silicon-based technology. In this chapter, the luminescent characteristics of SRN and SRO films deposited by low‐pressure chemical vapor deposition are reviewed and discussed. SRN and SRO films, which exhibit the strongest photoluminescence (PL), were chosen to analyze their electrical and electroluminescent (EL) properties, including SRN/SRO bilayers. Light emitting capacitors (LECs) were fabricated with the SRN, SRO, and SRN/SRO films as the dielectric layer. SRN‐LECs emit broad EL spectra where the maximum emission peak blueshifts when the polarity is changed. On the other hand, SRO‐LECs with low silicon content (~39 at.%) exhibit a resistive switching (RS) behavior from a high conduction state to a low conduction state, which produce a long spectrum blueshift (~227 nm) between the EL and PL emission. When the silicon content increases, red emission is observed at both EL and PL spectra. The RS behavior is also observed in all SRN/SRO‐LECs enhancing an intense ultraviolet EL. The carrier transport in all LECs is analyzed to understand their EL mechanism.
Part of the book: Luminescence
Graphene is a ground‐breaking two‐dimensional (2D) material that possesses outstanding electrical, optical, thermal, and mechanical properties and that promises a new generation of devices. Despite all these, some applications require graphene‐based materials with different characteristics, such as good solubility in organic solvents and a specific band gap to be dispersible in polymer nanocomposite matrix and applied as active layer, electron transport layer (ETL) or hole transport layer (HTL) in organic photovoltaics. Chemically modified graphene derivatives are studied, searching for better dispersions and even more properties for different applications. Most of the attention has been drawn to dispersions of graphene oxides or highly reduced graphene oxides. Therefore, this allows an opportunity to study the characteristics of materials with intermediate oxidation degrees and its applications.
Part of the book: Graphene Materials