Investigation On PSCs With Low Temperature Printable Carbon As Counter Electrode And DSSCs With Novel Pyridinium Cationic Dyes As Light Harvester

More recently, benefiting from organometal halide perovskite absorbers'(ABX3 (A= MA+, FA+; B= Pb2+, Sn2+, Ge2-; X= Cl-, Br-, I-)) appealing advantages of intensive light absorption, small binding energy, and long charge diffusion length and lifetime, landmark breakthrough with certified efficiencies over 22% has been brought forth in the field of all solid solar cells. Nonetheless, it still encountered challenges of expensive raw materials, toxicity of Pb, interfaces energy barriers as well as the poor device stability. In this thesis, we communicate a strategy to dissolve the cost issues facing perovskite solar cells (PSCs) in device fabrications. The low temperature (=100?) printable processed carbon paste was developed as counter electrode in TiO2/CH3NH3PbI3 heterojunction perovskite solar cells (PSCs) to substitute the noble metallic materials and avoid the application of expensive hole transporting materials (HTMs) for the first time. Under optimized conditions, the devices afforded an impressive PCE of 8.31%. Moreover, the devices with carbon as counter electrode demonstrated excellent stability over 800 h under irradiation of natural sunlight. The EIS measurements disclosed the excellent capability in charge transportation. This work presented here offered promise for the scalable production of PSCs.The low temperature printable carbon counter electrode based PSCs was for the first time interfacial engineered with cost-effective, dopant-free copper phathalocyanine (CuPc) nanorod. The testing results revealed that the energy barrier between the CH3NH3PbI3 and carbon was well eliminated. And the CuPc nanorods were found to be effective in facilitating charge separation and suppressing charge recombination. As a result, an efficiency of 16.1% with good stability was demonstrated, which is one of the highest efficiencies for carbon counter electrode-based PSCs. The work presented here demonstrates important step forwards to practical applications for PSCs, as it paves the way for development of cost-effective, stable and highly efficient PSCs.A kind of noble metal-free, vacuum-free, cost effective, greatly stable and highly efficient PSCs by incorporating a novel HTM TPDI (5,10,15-triphenyl-5H-diindolo[3,2-a:3',2'-c]carbazole) and low temperature processed carbon as cathode was developed for the first time. This newly explored HTM TPDI can be synthesized by a simply facial route with low cost. Detailed studies revealed its good solubility, excellent thermal stability, high hole mobility (two order of magnitude higher than Spiro-OMeTAD) and suitable energy level alignment with CH3NH3PbI3 and carbon cathode. The photovoltaic characteristics of TPDI based PSCs were systematically compared with those of Spiro-OMeTAD based ones. TPDI can work well both in doped and pristine forms and optimized PCEs of 15.5% and 13.6% were achieved, respectively, which are comparable to or even better than those of the devices employing doped or pristine Spiro-OMeTAD as HTM under identical conditions. Moreover, TPDI based PSCs exhibited excellent durability during the long term stability measurements for 30 days.To date, extensive efforts have been made to pursue high photovoltaic efficiency and low cost for dye sensitized solar cells'(DSSCs') commercial attractiveness. The dye sensitizers anchored on the surface of a wide band gap semiconductor govern photon harvesting and electron conversion, being one of the decisive factors to high photon conversion efficiency. Therefore, it is rather desirable to design and synthesize cost-effective, stable and highly efficient photosensitizers from the perspective of scalable production of DSSCs. In this thesis, metal-free dye sensitizers incorporating pyridinium cation as electron acceptor were rationally structural engineered with different aliphatic chains branched donor groups to balance (or elevate) the "trade-off'effects between the photocurrent and the photovoltage, which is induced by the pyridine cation. The results demonstrated that the constructed double building block layers were efficient in suppressing the intimate contact between electrons injected into the TiO2 and the electrolyte mediators, which finally retarded fast recombination and prolonged the electron lifetime, thereby contributed significantly to the enlarged JSc and Voc. Accordingly, dye ZF203 afforded the highest PCE of 8.8%, which is also one of the highest efficiencies with pyridine cation as electron acceptor. Moreover, benefiting from the efficient intramolecular energy transfer (EnT), dye ZF204 afforded the highest JSC of 15.2 m·cm-2.