In this study, amorphous Ti-doped WO₃ films with interpenetrated porous networks were successfully fabricated via a facile sol–gel method by using a hydrolysis-tolerant titanium coupling agent (TCA) as a Ti-dopant.

The defects present in solution-processed perovskite light absorbing materials are responsible for deteriorating the performance and stability of perovskite solar cells. Therefore, suppressing the defect formation and passivating the pre-existing defects in perovskite materials are of paramount importance in pushing the efficiency of perovskite solar cells (PSCs) toward the theoretical limit and ensuring the long-term stability of PSCs. In this work, we report an efficient defect passivation route using a bidentate small organic molecule, pyrazine, which is capable of making either a monodentate or a bridging bidentate bond with under-coordinated Pb²⁺ ions mainly present in the surface and grain boundaries of perovskite films. The various analyses for the defect density and charge carrier lifetime of perovskite light absorbing layers demonstrated that pyrazine effectively passivated defects existing on the surface and grain boundaries of the perovskite films without affecting the morphology and crystallinity via a simple post-treatment procedure. As a result, the best untreated device obtained a power conversion efficiency of 19.14%, while an efficiency of 20.58% was achieved when pyrazine treated.

Acetylene-black paste without a light scattering layer was applied to meso-porous TiO₂ photo-electrode films with a crystalline framework, a low residual carbon, and a tunable morphological pore size. The thermal-treated TiO₂ photo-electrode films had an increased acetylene-black concentration with an increase in artificial pores and a decrease in residual carbon. The performance of dye-sensitized solar cells (DSSCs) was enhanced by the use of the TiO₂ photo-anode pastes at various acetylene-black concentrations. The photo-conversion efficiency of the DSSCs using TiO₂ photo-electrode films with 1.5 wt% acetylene-black was enhanced from 7.98 (no acetylene-black) to 9.75% without the integration of a light- scattering layer.

As DSSCs are vulnerable to continuous irradiation of Ultra Violet (UV) light, for outdoor stability, a UV cut-off filter is vital to shield the UV light under outdoor conditions. Unfortunately, the large drop in photo-conversion efficiency by the UV cut-off is inevitable to maintain the outdoor stability. Herein, we propose a novel UV conversion layer using a unique combination of spectrum conversion materials with UV absorbing 1,8-naphthalimide derivatives in poly(ethylene-co-vinyl acetate) on the photo-anode. This functional layer has shown unique characteristics which form exciton complex molecules at high concentration under UV absorption. As a result of converting absorbed UV light to a visible light source for the sensitizing dye, the relative efficiency of the proposed DSSCs have shown comparable initial photo-conversion efficiency to bare DSSC and maintained 18% higher relative photo-conversion efficiency after 48 days outdoor conditions compared to a DSSC using a commercial UV cut-off filter.