| abstract |
Articles and methods for increasing the triplet upconversion threshold, e.g., by utilizing a triplet exciton acceptor lower in energy than the sensitizer or upconverter, are generally described. Some embodiments, for example, are directed to articles and methods that use a triplet sensitizer, an upconverter, and an acceptor to produce upconverted photons (e.g., light of a second energy). The light can be used to polymerize a polymerizable species. Other upconversion configurations can also be used in other embodiments. In some cases, this may allow true 3D printing to be achieved due to improved control of light absorption, e.g., without needing to "print" on a layer- by-layer basis. |