We report a method for fabricating predefined photopatterns of upconversionnanophosphors using a chemical amplification reaction for direct writingof films with multilayer color-coded patterning for security applications.To photopattern the nanocrystal film we have synthesized rare-earth ion (Er3+/Yb3+ orTm3+/Yb3+) co-doped sodiumyttrium fluoride (α-NaYF4)nanophosphors and functionalized the nanocrystal surfaces by incorporation of a photopatternable ligandsuch as t-butoxycarbonyl (t-BOC). The surface modification allows photopatterning of the nanophosphor solid statefilm. Furthermore, upconversion nanophosphors show a nearly quadratic dependence of theupconversion photoluminescence (PL) intensity on the excitation light power,and tailoring of the PL wavelength is possible by changing the lanthanide ions.We have demonstrated the capability of anchoring nanophosphors at desirablelocations by a photolithography technique. The photopatterned films exhibit fixednanophosphor structures clearly identifiable by strong upconversion photoluminescenceunder IR illumination which is useful for a number of applications in security.