NOVELTY - Polymeric linking agent solution comprises a polymeric linking agent, metal oxide nanoparticles, and a solvent. The solution contains the polymeric linking agent in a concentration to interconnect at least a portion of the metal oxide nanoparticles at below 300 degrees C.    USE - The polymeric linking agent is used for forming interconnected nanoparticles useful for making a flexible photovoltaic cell (claimed).    ADVANTAGE - The polymeric linking agent enables the manufacture of photovoltaic cells at low temperatures on flexible substrates, e.g. polymeric substrates. Co-sensitizers that co-adsorb with a sensitizing dye to the surface of an interconnected semiconductor oxide nanoparticle material increase the efficiency of photovoltaic cells by improving their charge transfer efficiency and reducing the back transfer of electrons from the interconnected semiconductor oxide nanoparticle material to the sensitizing dye.    DETAILED DESCRIPTION - Polymeric linking agent solution comprises a polymeric linking agent of formula, -(O-M(OR) i-) m-; metal oxide nanoparticles of formula, M xO y; and a solvent. The solution contains the polymeric linking agent in a concentration to interconnect at least a portion of the metal oxide nanoparticles at below 300 degrees C.    i, m, x, and y=integers greater than 0;    M=Ti, Zr, Sn, W, Nb, Ta, or Tb;    R=H, alkyls, alkenes, alkynes, aromatics, or acyls.    INDEPENDENT CLAIMS are also included for:    (a) a method of interconnecting nanoparticles at low temperature, which comprises providing a solution comprising a polymeric linking agent and a solvent; and contacting metal oxide nanoparticles with the solution at below 300 degrees C to interconnect at least a portion of the metal oxide nanoparticles;    (b) a flexible photovoltaic cell comprising a photosensitized interconnected nanoparticle material and a charge carrier material, both disposed between first and second flexible light transmitting substrates;    (c) an electrolyte composition for use in a solar cell, which comprises a gelling compound comprising a metal ion, and an organic compound capable of complexing with the metal ion at several sites;    (d) a method of gelling an electrolyte solution for use in a dye-sensitized solar cell, which comprises providing an electrolyte solution, adding the to electrolyte solution a material capable of complexing at several sites, and adding to the electrolyte solution a metal ion that complexes at the sites, thus forming a gel;    (e) a method for reducing electron transfer to species within the electrolyte of a solar cell, which comprises providing a photovoltaic cell portion comprising a dye-sensitized layer, providing an electrolyte solution, adding a metal-anion compound to the electrolyte solution in amounts to form a gel electrolyte, and adding the gel electrolyte to the photovoltaic cell portion;    (f) a method of forming a semiconductor oxide nanoparticle layer on a base material, which comprises coating a base material with a primer layer comprising a semiconductor oxide, and applying semiconductor oxide nanoparticles on the primer layer at below 300 degrees C, where the primer layer improves adhesion of the semiconductor oxide nanoparticles to the base material;    (g) a nanoparticle layer formulation for a photovoltaic cell, which comprises a nanoparticle material dispersed in a solvent, a polymeric binder soluble in the solvent, and a base material on which is disposed a solution comprising the nanoparticle material and the polymer binder to form a mechanically stable nanoparticle film;    (h) a method of forming a nanoparticle layer in a photovoltaic cell, which comprises providing a nanoparticle material dispersed in a solvent, dispersing a polymer binder in the solvent, and applying a solution comprising the nanoparticle material and the polymer binder to a base material;    (i) a photosensitizing agent for a photovoltaic cell, which comprises a sensitizing dye for receiving electromagnetic energy, and a co-sensitizer comprising a coordinating group for co-adsorbing with the sensitizing dye on a surface;    (j) a photosensitized nanoparticle layer in a photovoltaic cell, which comprises a sensitizing dye for receiving electromagnetic energy, a co-sensitizer including a coordinating group, and an interconnected nanoparticle material comprising a surface for co-absorbing the sensitizing dye and the co-sensitizer to form a photosensitized nanoparticle layer; and    (k) a method of forming a photosensitized nanoparticle layer in a photovoltaic cell, which comprises providing a sensitizing dye for receiving electromagnetic energy, and co-adsorbing a co-sensitizer on a surface of an interconnected nanoparticle material to form a photosensitized nanoparticle layer.