Research On Low-cost, Stable, Efficient And Environmental Friendly Dye And Perovskite Sensitized Solar Cells

When developing towards commercial application, dye or peroskite sensitized soalr cells require peroperties of low-cost, high stability, economic fabrication process and low toxicity apart from efficiency. Aiming to reach these goals in this dissertation, we prepared novel, low-cost, environmentally friendly materials for efficient dye-sensitized solar cells (DSSCs), and explored facile but effective device technology for highly stable perovskite solar cells (PSCs). There are four works which involve both DSSCs and PSCs summarized as follows:We introduced a facile but effective method to prepare the hydroquinone (HQ)/ benzoquinone (BQ) redox couple based electrolyte in DSSCs in the open air via acetic acid (HAc) treatment. Under simulated one sun irradiation (100 mW cm-2, AM 1.5 G), the HAc treated HQ/BQ based electrolyte achieved a device efficiency of 5.82% which is 114% enhanced compared to the untreated one. Moreover, DSSCs employing this HAc treated HQ/BQ based electrolyte exhibited higher current and better charge transfer in contrast to traditional Ⅰ2 based electrolyte. Followed research on electrolyte based on derivatives of HQ/BQ moleculars showed that alkane substitution trend to enhance the performance of DSSCs with a slightly increased efficiency of 5.88%. The HAc treated HQ/BQ based electrolyte contributes to DSSCs with advantages of considerable efficiency, facile process, compatible with frequently-used dye N719 and diversity of molecular design, so that is a promising alternative to Ⅰ2 based electrolyte for efficient DSSCs.Inspired from the photosynthesis, we prepared an Ⅰ2-free electrolyte based on a highly environmentally-friendly material ubiquinone 10 (UQ10) and assembled DSSCs. Under simulated one sun irradiation measurement, this UQ10 based electrolyte leaded to a 10% enhanced efficiency of 8.18% compared with the most common one using Ⅰ2 (7.44%). Revealed by photoelectrochemical characterizations, we can attribute this enhancedment of this UQ10 based electrolyte to its lower visible light absorption and good catalytic activity at the counter electrode surface. Besides, as a widely used raw material in cardiovascular medicine and cosmetics, UQ10 means low-cost and enrivonmental friendly for DSSCs. DSSC employing the UQ10 based electrolyte is advantageous owing to high efficiency, good bio-safety, universal sensitizers compatibility and diversified molecular design, so that is very promising for further application of DSSCs.We have demonstrated a facile yet effective way to mitigate the instability of perovskite solar cell via device structure design and contact engineering. By adopting the hole-conductor layer-free structure of PSC and a unique bi-layer hybrid carbon back contacts, our devices exhibited excellent stability which can inhibite moisture ingression and heat-induced perovskite degradation. Under thermal stress at 100℃ for 30min, our designed PSCs showed increased performance instead of degradation. The optimized cell achieved a final efficiency of 13.6% from an initial efficiency of 11.3% after heat treatment. Upon simple encapsulation, these devices could not only remain 90% of the initial efficiencies after water exposure but over 100% initial efficiency heated at 150℃ for 30 min. Demonstrating excellent thermal and moist cell stability, our approach may open a door for viable commercialization of the emerging PSC technology.In order to provide a nichetargeting approach to furtherly enhance the performance of hole-conductor free PSCs, we designed a novel composite nanostructured TiO2 based electron-transport layer (ETL) by the combining size blended nanoparticles (SBNP) and nanoarrays (NA). And the specially designed composite nanostructured (SBNP+NA) ETL was successfully used in the hole-conductor free PSCs, which achieved very stable cells with an optimal efficiency of 13.5%. The enhanced performance could be attributed to the quicker charge transport and lower recombination in the composite ETL. In spite of the stable high efficiency, PSCs using SBNP+NA ETL achieved further advantages of low cost, facile all-solution fabrication process in the open air and high reproducibility.