Quasi-Solid-State Dye-Sensitized Solar Cells by Mechanically Stable Semi-Interpenetrating Network Polymer Gel Electrolytes for Indoor Applications

Herein, the copolymer composition of [AN] and [4VP] units of [P(AN- co -4VP)] 2 - b -PEO (here, AN = acrylonitrile, 4VP = 4-vinylpyridine, and PEO = poly(ethylene oxide)) block copolymer (BCP) was controlled by reversible addition–fragmentation chain transfer (RAFT) polymerization to make it acetonitrile-soluble BCP so that this BCP can be further converted into in situ three-dimensional (3D) network polymer gel electrolytes (PGEs) inside the cell by quaternization reaction in acetonitrile-based liquid electrolyte media. Before in situ application, a fully semisolid 3D network polymer gel with high mechanical stability was obtained by optimizing the quaternization reaction conditions in an iodine liquid electrolyte medium. The excess cross-linking agent, 1,8-diiodooctane, was utilized to ensure a fully quasi-solid-state gel by chemical cross-linking in the presence of iodine and tert -butylpyridine (TBP) of the liquid electrolyte. The addition of liner PEGDME (average MW 2000) in a cross-linking polymer further enhances the mechanical stability of the network PGE. A remarkable photovoltaic performance, above 7% efficiency, was found for quasi-solid-state dye-sensitized solar cells (QSS-DSSCs) under 1 sun conditions, around 20% lower than that for volatile liquid-state DSSCs. However, the deviation of efficiency for QSS-DSSCs by using in situ 3D semi-IPN PGE was reduced to 10% with liquid-state DSSCs under compact fluorescent lamp (CFL) ambient light. 16–20% efficiency of QSS-DSSCs by in situ semi-IPN PGE under CFL light intensity of 200–2000 lx can be entirely satisfactory in terms of flexibility and mechanical stability of the device, which ensures the potential of these QSS devices to power indoor-placed wireless devices and low-powered consumer electronic devices.