This course introduces the basic principles of photon upconversion and the current state of upconversion nanomaterials. It will focus on rare-earth doped nanophosphors as well as on their emerging applications. We will describe the use of nanophotonic concepts to manipulate excitation dynamics and guide nanochemistry to make a hierarchically built new generation of rare-earth of doped nanoparticles. We call these photon nanotransformers, with highly efficient frequency conversion of infrared (IR) light from a low power cw light source into visible or ultraviolet (UV) light. These photon nanotransformers open up numerous opportunities such as in high contrast bioimaging, photodynamic therapy, remote photoactivation, displays, anti-counterfeiting, biosensing, drug release and gene delivery, as well as in solar cells. They exhibit the following merits : (1) They utilize light excitation in near IR and can produce upconverted emission also in NIR, both being within the "optical transparency window" of tissues, and therefore provide high contrast 3D in vitro and in vivo imaging; (2) The naked eye is highly sensitive in the visible range, while it has no response to the NIR light, creating interest in NIR to visible frequency upconversion for security and display applications; (3) Frequency upconversion of IR to visible can be useful for IR photon harvesting, as current solar devices do not utilize IR. It is also useful for night vision (4 ) IR to UV upconversion has potential applications in photocleavage for drug /gene release, and 3D volume curing of photoactive resins for industrial and dental applications.
This course introduces the basic principles of photon upconversion and the current state of upconversion nanomaterials. It will focus on rare-earth doped nanophosphors as well as on their emerging applications. We will describe the use of nanophotonic concepts to manipulate excitation dynamics and guide nanochemistry to make a hierarchically built new generation of rare-earth of doped nanoparticles. We call these photon nanotransformers, with highly efficient frequency conversion of infrared (IR) light from a low power cw light source into visible or ultraviolet (UV) light. These photon nanotransformers open up numerous opportunities such as in high contrast bioimaging, photodynamic therapy, remote photoactivation, displays, anti-counterfeiting, biosensing, drug release and gene delivery, as well as in solar cells. They exhibit the following merits : (1) They utilize light excitation in near IR and can produce upconverted emission also in NIR, both being within the "optical transparency window" of tissues, and therefore provide high contrast 3D in vitro and in vivo imaging; (2) The naked eye is highly sensitive in the visible range, while it has no response to the NIR light, creating interest in NIR to visible frequency upconversion for security and display applications; (3) Frequency upconversion of IR to visible can be useful for IR photon harvesting, as current solar devices do not utilize IR. It is also useful for night vision (4 ) IR to UV upconversion has potential applications in photocleavage for drug /gene release, and 3D volume curing of photoactive resins for industrial and dental applications.
