Fig. 1 Schematic of the DSSC structures

Fig. 2 Schematic of the electron transfer and recombination processes Solid lines for transfer and dashed lines for recombination

Fig. 3 HR-TEM images of the microstructure of the interparticle connections between the P25 particles (a) and the smaller nanoglue particles (b)[10] (a) Image of nanoglue TiO2 particles located in between the P25 partcles; (b) Boundaries of the nanoglue and P25 particles with arrows

Fig. 4 Relationship between the pressure applied to the TiO2 film and the performance of the fabricated plastic-substrate DSC (a) and transmittance of ITO-PEN films with and without an AR film (b)[21]

Fig. 5 Microscopies of electrophoretically deposited P-90 TiO2 nanostructure on ITO/PEN film by one-step process (a) and two-step process (b)[25]

Fig. 6 Transient photovoltage measurements of the DSSCs with various TiO2 electrodes prepared with or without 0.1wt% MWCNT[30]

Fig. 7 XRD patterns of the as-deposited ALD TiO2 overlayer of three different thicknesses (5, 10 and 15 nm) on 3 μm mesoporous SiO2 films[31] The inset schematic depicts the ALD TiO2 deposited on a silica mesoporous template with the dashed lines indicating the electron transport pathways

Fig. 8 Digital photograph of a prototype DSPVW and its schematic cross section (a), top view (b) and cross-sectional (c) FESEM images of TiO2 nanotube arrays grown around a Ti wire fabricated by anodization at 60 V for 12 h[45]

Fig. 9 Illustration of the designed fabrication and transfer procedure using free-standing film method (A) and cross-sec-tional FESEM mage of a piece of free-standing flexible TiO2 nanowire film (B) (inset figure), showing layered structure with small and big NWs on the top and bottom, respectively[53]