A Mechanoresponsive Phase‐Changing Electrolyte Enables Fabrication of High‐Output Solid‐State Photobioelectrochemical Devices from Pigment‐Protein Multilayers. Issue 5 (18th December 2017) - Ravi, Sai Kishore
Abstract: Exploitation of natural photovoltaic reaction center pigment proteins in biohybrid architectures for solar energy harvesting is attractive due to their global abundance, environmental compatibility, and near‐unity quantum efficiencies. However, it is challenging to achieve high photocurrents in a device setup due to limitations imposed by low light absorbance by protein monolayers and/or slow long‐range diffusion of liquid‐phase charge carriers. In an attempt to enhance the photocurrent density achievable by pigment proteins, here, an alternative solid‐state device architecture enabled by a mechanoresponsive gel electrolyte that can be applied under nondenaturing conditions is demonstrated. The phase‐changing electrolyte gel provides a pervading biocompatible interface for charge conduction through highly absorbing protein multilayers that are fabricated in a simple fashion. Assembled devices exhibit enhanced current stability and a maximal photoresponse of ≈860 µA cm −2, a fivefold improvement over the best previous comparable devices under standard illumination conditions. Photocurrent generation is enhanced by directional energy transfer through extended layers of light‐harvesting complexes, mimicking the modular antenna/transducer architecture of natural photosystems, and by metastable radical pair formation when photovoltaic reaction centers are embedded throughout light‐harvesting regions of the device. Abstract : A mechanoresponsive electrolyte exhibits a reversible mechano‐induced solid‐to‐liquid phase transition. The phase‐changing gel electrolyte provides a pervading biocompatible interface for charge conduction through highly absorbing engineered protein multilayers in a solid‐state device under non‐denaturing conditions. Photocurrent generation is enhanced by directional energy transfer through extended layers of light‐harvesting complexes, mimicking the modular antenna/transducer architecture of natural photosystems.