a b s t r a c tPhotovoltaic technologies represent one of the leading research areas of solar energy which is one of the most powerful renewable alternatives of fossil fuels. In a common photovoltaic application the batteries play a key role in storage of energy generated by solar panels. Although it will take time for dye sensitized solar cells (DSSCs) and batteries based on biopolymer electrolytes to take their places in the market, laboratory studies prove that they have a lot to offer. Most efficient DSSCs and batteries available in market are based on liquid electrolytes. The advantages of liquid electrolytes are having high conductivity and good electrode-electrolyte interface whereas, disadvantages like corrosion and evaporation limit their future sustainability. Biopolymer electrolytes are proposed as novel alternatives which may overcome the problems stated above. In this review, we focus on fabrication, working principle as well as up to date status of DSSCs and batteries using biopolymer electrolytes. The effects of structural and electrical properties of biopolymer based electrolytes on the solar energy conversion efficiencies of DSSCs and their compatibility with lithium or other salts in battery applications are summarized. Biopolymer electrolyte based DSSCs are categorized on the basis of types of additives and recent outcomes of author's laboratory studies on biopolymer electrolyte based DSSCs and batteries are also presented.

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Fibrous mechanosensing elements can provide information about the direction of crack propagation and the mechanism of material failure when they are homogeneously dispersed into the bulk volume of materials. A fabrication strategy of fibrous systems showing triboluminescent (TL) responses is in high demand for such applications. In this work, micrometer-sized Cu(NCS)(py) 2 (PPh 3 ) crystals were synthesized, and polymeric fibrous mats containing the TL crystals were obtained via electrospinning as a stress probe for the determination of mechanical impact. Four different polymeric systems have been employed (PMMA, PS, PU, and PVDF), and the mechano-optical sensing performance of electrospun mats of the polymer-crystal composites was measured. Photophysical properties (quantum yield, band gap, and broadness of the emission) of the TL crystal/electrospun mat composites were also studied. TL and PL emission maxima of the PU-based composite mat show identical behavior due to the chemical affinity between the two structures and the smallest fiber diameter. Moreover, the PU fiber mats exhibit long-lived bluish-green emission persisting over a large number of drops.

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Ethynylene-bridged perylene diimides (PDIs) with different sized silane groups have been synthesized as a steric blocking group to prevent the formation of non-radiative trap sites, for example, strong H-aggregates and other dimers or excimers. Excited singlet-state exciton dynamics were investigated by time-resolved photoluminescence and ultrafast pump–probe transient absorption spectroscopy. The spectra of the excimer or dimer aggregates formed by the PDIs at high concentrations were also determined. Although the photophysical properties of the bare and shielded PDIs are identical at micromolar concentrations, more shielded PDI2 and PDI3 exhibited resistance to aggregation, retaining higher photoluminescence quantum yield even at 10 mM concentration and in neat films. The PDIs also exhibited high photostability (1 h of continuous excitation), as well as electrochemical stability (multiple cycles with cyclic voltammetry). Prevention of dimer/aggregate formation in this manner will extend the uses of PDIs to a variety of high concentration photonics and optoelectronic applications, such as organic light-emitting diodes, organic photovoltaics, and luminescent solar concentrators.