دانلود کتاب تبدیل نانوذرات از مبانی به کاربردها

The conversion of low-energy photons into high-energy photons, known as “frequency upconversion,” using advanced optical materials has become an emerging research field with wide consequence and impact in various scientific areas ranging from healthcare to energy and security. The materials showing frequency upconversion properties are known as upconversion (UC) materials. UC materials reveal variety of applications in different fields, viz. color display, two-photon imaging in confocal microscopy, WLEDs, high-density optical data storage, upconvertors, under sea communications, solid-state lighting, sensors, photovoltaics, photocatalysis, food industry, indicators, anti-counterfeiting, bioimaging, cancer therapy and other biological fields. It is known that in comparison to ultraviolet (UV) and visible light the near-infrared (NIR) light is abundant and non-destructive in nature. It has deep penetration in the organisms and less harmful quality. UC luminescent materials in nanosize range are known as UC nanomaterials or UC nanoparticles (UCNPs). UCNPs excited with non-destructive NIR light are a better choice than the conventional downconversion nanoparticles because they are free from autofluorescence, have low light penetration, and cause less severe photo-damage to living organisms. It is notable to mention that the low efficiency of UC materials definitely becomes a major barrier for their application in a wide range. For researchers, it is a top priority to overcome this problem. Several engineered UCNPs, e.g. organic, inorganic, hybrids, and thin films, have been explored widely to obtain highly efficient UC luminescent materials. Usually, organic luminescentmaterials suffer poor stability under harsh conditions and have poor long-term reliability, but have a greater ductility than inorganic materials. The inorganic luminescent materials are more durable and possess high thermal stability. So, the hybrid materials consisting of both inorganic and organic components, namely, metal organic frameworks (MOFs), have attracted researchers with enhanced luminescence properties as compared to the bare organic and inorganic materials.