https://www.selleckchem.com/products/DMXAA(ASA404).html Despite tremendous progress in the field of fluorescence-based anticounterfeiting, the advanced anticounterfeiting techniques are still posing challenges all over the world due to their cost and reliability. Recently, light-emitting atomically precise nanoclusters have emerged as attractive building blocks because of their well-defined structure, function, and stable photoluminescence. Herein, we report the room temperature fabrication of a stable, flexible, nontoxic, and low-cost precision nanocluster-based luminescent ink for the stencil printing of an optically unclonable security label. Nanocluster-based printing ink shows brilliant photoluminescence owing to its extended C-H···π/π···π interactions. Spectroscopic and microscopic investigations show that intercalated nanoclusters in the printed security labels are highly stable as their optical features and molecular compositions are unaffected. The exceptional mechanical, thermal, photo, and aqueous stabilities of the printed security labels endorse to demonstrate the printing and smartphone-based electronic reading of the quick response code on a currency. Finally, confidential information protection and decryption under a precise window of light have been achieved by adopting the optical contrast illusion. The overall cost of the security label is found to be approximately 0.013 USD per stamp.Protein-based electronic biomaterials represent an attractive alternative to traditional metallic and semiconductor materials due to their environmentally benign production and purification. However, major challenges hindering further development of these materials include (1) limitations associated with processing proteins in organic solvents and (2) difficulties in forming higher-order structures or scaffolds with multilength scale control. This paper addresses both challenges, resulting in the formation of one-dimensional bundles composed of electrically conductiv