Enhanced Optical Properties via Energy Transfer of Layered Biomaterial/Metal-Organic Framework Composites

Abstract

Metal-organic frameworks (MOFs) are intriguing materials with outstanding structural tunability and high surface areas, making them potentially suitable for different optoelectronic applications. However, they are also considered nanoporous materials, which can significantly influence their optical properties and applications. This work successfully investigates the photophysical properties of layer-by-layer (LbL) composites formed by a LbL structure of chicken albumen (egg white) with three distinct metal-organic frameworks (MOFs): (a) Zinc(II)-based MOF ({[Zn-2(Htpim)(3,4-pydc)(2)]<middle dot>4DMF<middle dot>4H(2)O}), (b) zinc(II)-based thermochromic MOF heated at 150 degrees C, and (c) Eu-based MOF ([Eu(H2O)(C2O4)(0.5)(HPO3)]<middle dot>H2O). Photoluminescence (PL) analysis demonstrated a 3-fold increase when chicken albumen was added to the MOF LbL composites compared to the pristine MOFs. Aside from the optical enhancements, a clear spectral overlap was measured from the PL and absorption spectra of albumen and the three MOFs, identifying a Forster-type resonance energy transfer (FRET). After carefully optimizing the stacking of albumen/MOF LbL composites, it revealed a broadband white light emission with a CIE index of (0.312, 0.366) and (0.303, 0.352). These results highlight the demonstration of energy transfer in biomaterial-MOF LbL composites for the in-depth study and capability for fabricating bioinspired white light emitters.