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This review presents a comprehensive account of the research scenario in the ferromagnetic (FM) behavior displayed at room temperatures (RT) in the metal oxides (MOx) for spintronics applications. Spintronic devices need simultaneous manipulation of charge and spin of the electron and the material needed for the fabrication of such devices must show the existence of FM behavior at or above RT. This article discusses the induction of room temperature FM (RTFM) behavior in MOx via doping and co-doping of magnetic and non-magnetic ions. The semiconductor doped with magnetic ions (usually up to maximum 10%) are well known as dilute magnetic semiconductors (DMSs) whereas they are known as d0 FM materials with doping of non-magnetic ions. This review mainly focuses on the MOx based DMSs. The various mechanisms and models for the induction of RTFM in such systems are discussed followed by their advantages and drawbacks along with their technological applications. However, a short discussion on RTFM behaviors of d0 materials is also presented. Further, the influence of various morphologies on RTFM behavior of MOx followed by the RTFM in 2D-MOx is also discussed. [ABSTRACT FROM AUTHOR]

This study presents the synthesis of ZnSe nanoparticles (NPs) via precursor solution method; preparation of perovskite and ZnSe:perovskite composites (0, 2, 4, and 6 mg/ml, respectively) via solution processing method. The synthesis of these materials has been confirmed by X-ray diffraction/XRD, UV–Visible spectroscopy, steady-state photoluminescence (PL) spectroscopy, time-resolved photoluminescence (TRPL) spectroscopy, contact angle analysis and scanning electron microscopy/SEM. As-synthesized ZnSe:perovskite composites have been deployed in the fabrication of solar cells. SEM micrographs of these composites have shown a significant reduction in extrinsic defects of perovskite films on incorporation of ZnSe NPs into perovskites matrices indicating improvement in morphology. The contact angle analysis confirmed a significant decrease in the hydrophilicity as contact angle is increased by ~ 10° as compared to that of pristine perovskite. Moreover, TRPL spectroscopy confirmed a modest increase in the lifetimes and hence, reduction in the recombination rate within ZnSe:perovskite composites. Likewise, J-V curve of as-fabricated devices demonstrates an improvement in the performance with the increase in the concentration of ZnSe NPs into perovskite. The best device based on these composites has shown an efficiency of 5.98%, open circuit voltage/Voc of 0.931 V, short circuit current density/JSC of 9.82 mA/cm2 and fill factor/FF of 65.50% which has retained 79.6% of its actual efficiency after 30 days of air exposure. [ABSTRACT FROM AUTHOR]

The present paper reports the fabrication of solar cells using surface-optimized ZnS-Perovskite composites. Initially, ZnS nanorods (NRs) were synthesized via precursor thermolysis route. Further, these ZnS NRs were used to prepare different ZnS-CH3NH3PbI3 composites (0, 2, 4, and 6 mg/ml). The synthesis of ZnS NRs and ZnS-CH3NH3PbI3 composites was confirmed by XRD, scanning electron microscopy/SEM, and UV–Visible/Photoluminescence (PL) spectroscopy techniques. The SEM micrographs suggested that the grain size increases with the increase in the concentration of ZnS NRs into perovskite matrices resulting reduction in grain boundary problem. The J–V curve of as-fabricated solar devices has demonstrated the significant enhancement in overall photovoltaic performance. The best performing device has shown an open-circuit voltage/Voc of 0.81 V, short-circuit current density/Jsc of 9.64 mA/cm2, fill factor/FF of 63.43%, power conversion efficiency/PCE (η) of 4.95%, shunt resistance/Rsh of 4591 Ω-cm2, and series resistance/Rs of 22.1 Ω-cm2. It retained ~ 80% of its original efficiency after 30 days of exposure in ambient atmosphere. [ABSTRACT FROM AUTHOR]

Owing to promising optical and electrical properties and better thermal and aqueous stability, chalcogenide perovskites have shown a wide range of applications. Chalcogenides belong to the 16th group of periodic tables and could be potential materials for the fabrication of efficient and stable (chalcogenide perovskite) solar cells. Generally, metal halide perovskites are used for the fabrication of solar cells. However, they have some grave problems like less stability and toxicity. In this context, chalcogenide perovskites (AB (S, Se)3) may be a better option due to their potential to solve the existing problems and hence could be deployed in the fabrication of high-performance solar cells. These chalcogenide perovskites have high stability (thermal and aqueous), along with their environment-friendly elemental composition. In this review, we present various techniques used for the synthesis of chalcogenide perovskites and their applications in the fabrication of solar cells. Furthermore, we have also studied the scope for the commercial development of chalcogenide perovskite–based solar cell. [ABSTRACT FROM AUTHOR]

Quantum dots (QDs), the zero-dimensional semiconductor nanocrystals, due to their distinctive optoelectronic properties like size-tunable bandgap, broad absorption spectrum, size-dependent narrow emission profile, and better transport properties with the possibility of multiple exciton generation, have attracted wide attention as photosensitizers for developing QDs-sensitized solar cells (QDSSCs). Among all types of QDs, metal chalcogenide (MCh) QDs especially lead (Pb) and cadmium (Cd)-based chalcogenide QDs have been proven to be most suitable for the application as sensitizers in QDSSCs. This review paper presents a general overview of the QDSSC technology followed by the role of MCh QDs as the sensitizers in DSSCs. Despite their better sensitizing properties, lead (Pb)-based QDs have some serious issues such as lower stability and high toxicity associated with them. Therefore, this review is focused on Cd-based QDs (CdSe and CdTe) and presents a detailed prospective of recent trends in CdSe- and CdTe-based QDSSCs research. It tries to suggest the prospects of improvement strategies like co-sensitization of photoanode; deposition mechanisms, post-synthesis chemical treatments and doping/co-doping of sensitizers; optimization of synthesis parameters and interface modifications, etc. adopted for tailoring the bandgap of CdSe and CdTe QDs. [ABSTRACT FROM AUTHOR]

Tris (8-hydroxyquinolinato) aluminum (Alq3) is an organic electron transport and luminescent material. Even after more than 20 years of intense research and development, Alq3 continues to be one of the widely used organic light emitting diode (OLED) material. Metal doping/incorporation and nanoscale synthesis are the two popular strategies used to enhance the functional properties of Alq3. This review provides an understanding about the structure and properties of Alq3. It also tries to address the long-time unresolved issue regarding the origin of blue-shifted luminescence from γ and δ faces of Alq3. Metal doping/incorporation and nanoscale synthesis are the two widely adopted approaches to enhance the functional properties of Alq3. This review assesses the research done on these two strategies and attempts to understand the science behind adopting these strategies and the resulting performance enhancement. This review also provides an account of the research work undertaken on the relatively new direction that is nanoscale synthesis of metal-doped/incorporated Alq3 nanostructures which integrates the promises of nanoscale synthesis with the benefits of metal doping/incorporation. [ABSTRACT FROM AUTHOR]

We report the synthesis of amorphous (PbSe)100-xCdx (x = 5, 10, 15, and 20) nanoparticle thin films using thermal evaporation method under argon gas atmosphere. Thin films with a thickness of 20 nm have been deposited on glass substrates at room temperature under a continuous flow (50 sccm) of argon. X-ray diffraction patterns suggest the amorphous nature of these thin films. From the field emission scanning electron microscopy images, it is observed that these thin films contain quite spherical nanoparticles with an average diameter of approximately 20 nm. Raman spectra of these a-(PbSe)100-xCdx nanoparticles show a wavelength shift in the peak position as compared with earlier reported values on PbSe. This shift in peak position may be due to the addition of Cd in PbSe. The optical properties of these nanoparticles include the studies on photoluminescence and optical constants. On the basis of optical absorption measurements, a direct optical bandgap is observed, and the value of the bandgap decreases with the increase in metal (Cd) contents in PbSe. Both extinction coefficient (k) and refractive index (n) show an increasing trend with the increase in Cd concentration. On the basis of temperature dependence of direct current conductivity, the activation energy and pre-exponential factor of these thin films have been estimated. These calculated values of activation energy and pre-exponential factor suggest that the conduction is due to thermally assisted tunneling of the carriers. [ABSTRACT FROM AUTHOR]

Quantum confinement effect on the energy levels of Eu doped KCa(SO) nanoparticles has been observed. The broad photoluminescence (PL) emission band of Eu doped KCa(SO) microcrystalline sample observed at ∼436 nm is found to split into two narrow well resolved bands, located at 422 and 445 nm in the nanostructure form of this material. This has been attributed to the reduction in the crystal field strength of the nanomaterials, which results in widening the energy band gap and splitting the broad 4f5d energy level of Eu. Energy band gap values of the micro and nanocrystalline KCa(SO) samples were also determined by measuring the UV–visible absorption spectra. These values are 3.34 and 3.44 eV for the micro and nanocrystalline samples, respectively. These remarkable results suggest that activators having wide emission bands might be subjected to weak crystal strength via nanostructure materials to modify their electronic transitions. This might prove a powerful technique for producing new-advanced materials for use in the fields of solid state lasers and optoelectronic devises. [ABSTRACT FROM AUTHOR]