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Two novel zinc porphyrin dyes containing either benzotriazole or 2 H -[1,2,3]triazolo[4,5- c ]pyridine as auxiliary acceptors, respectively, were synthesized for dye-sensitized solar cells. These two auxiliary acceptors were firstly applied into porphyrin based dyes. The photophysical and electrochemical properties of the dyes were investigated. These two dyes show the whole visible light absorption when they are adsorbed on the TiO 2 film, which means that they are promising sensitizers for dye-sensitized solar cells. The absorption intensity of the triazolopyridine containing dye is higher than that of the benzotriazole containing dye, resulting in a better light harvesting. Thus, the dye-sensitized solar cell based on the former dye achieved higher conversion efficiency of 6.65% than the cell based on the latter dye (6.17%) with chenodeoxycholic acid as the coadsorbant. [ABSTRACT FROM AUTHOR]

Four novel D–π–A–π–A metal-free organic dyes Q1-Q4 were synthesized and the impacts of the auxiliary acceptors on the photovoltaic performances were studied. Q2 with quinoxaline as the auxiliary acceptor exhibited the best photovoltaic performance due to its highest short-circuit photocurrent density (17.22 mA cm −2 ), leading to a power conversion efficiency of 7.42% under simulated AM 1.5 G illumination. Q1 with the strongest electron withdrawing group (pyrazino[2,3- g ]quinoxaline) as the auxiliary acceptor showed the weakest performance, which can be attributed to electron trap and mismatch of energy-level. The results showed that the different electron-withdrawing property of auxiliary units significantly influenced the absorption, energy levels and photovoltaic performance. Incorporating auxiliary acceptor with moderate electron-deficient ability can extend the absorption range and adjust the molecular orbital energy levels, resulting in better photovoltaic performance. [ABSTRACT FROM AUTHOR]

Four novel organic dyes DT1-DT4 containing a dithienopyrrolobenzotriazole unit were synthesized and applied in dye sensitized solar cells, where dithienopyrrolobenzotriazole moiety was introduced as a π-spacer for the first time. The four dyes exhibited good light harvesting efficiency with high molar extinction coefficients and broad spectral response. The influence of the different electron donor on the photovoltaic performance was evaluated. The effects of the linear and branched alkyl chains in the π-bridge on the photophysical, electrochemical and photovoltaic performance were systemically investigated. The results show that branched alkyl chains are better than linear alkyl chains in inhibition of intermolecular aggregation and electron recombination between the injection electrons and electrolyte. Finally, DT4 sensitized solar cell obtained a power conversion efficiency of 8.05%. These results indicate that the dithienopyrrolobenzotriazole-based organic sensitizer is a promising candidate for efficient dye sensitized solar cells. [ABSTRACT FROM AUTHOR]

Abstract: Three organic dyes with double D–A system were synthesized and applied in the dye-sensitized solar cells. These dyes contain phenothiazine as an electron donor and cyanoacetic acid as an acceptor/anchor. Linkages were incorporated at the ortho-, meta- and para-positions and their impact on the performance of photovoltaic was observed. Among them, the dye with a para-position linkage exhibited the highest short-circuit photocurrent density (12.26 mA cm−2) and open-circuit photovoltage (756 mV), leading to the best overall efficiency (6.14%) due to better light harvesting capacity under standard global 1.5 AM conditions. Under similar measuring conditions the dyes with ortho and meta-position linkage delivered sunlight to electricity conversion efficiencies of 5.25% and 5.85% respectively. The result shows the position isomer of the linkage units influences the photophysical characteristics, dye loading on the film and electron lifetime. [Copyright &y& Elsevier]

Abstract Four novel benzotriazole-based donor-acceptor-donor (D-A-D) type hole transport materials (HTMs) BTA1-2 and DT1-2 are synthesized to investigate the effect of the acceptors on the photovoltaic performance of perovskite solar cells (PSCs). The acceptors include nonfused core (thiophene-benzotriazole-thiophene) and fused core (dithienopyrrolobenzotriazole, DTBT). Systematical investigation reveals that the acceptor greatly influences the absorption, energy level, hole transfer and extraction, and photovoltaic performances of the HTMs. The dopant-free HTMs DT1-2 with DTBT core exhibit better hole transfer and extraction performance, and then obtain better photovoltaic performance than that of BTA1-2. Especially, the PSC using DT2 without any dopants obtains a power conversion efficiency of 13.22%, which is outperforming than that of spiro-OMeTAD (10.41%). When doping with Li-TFSI/TBP (lithium bis(trifluoromethylsulphonyl)imide/tert-butylpyridine), DT2 -based cell achieves an improved efficiency of 15.77%. In addition, the different alkoxyl chain lengths on triphenylamine has a significant impact on the conductivity, hole mobility, hole extraction, and photovoltaic performance. The stability testing of the PSCs shows that the four HTMs based devices display improved stability than spiro-OMeTAD. These results certify that the fused acceptor core DTBT is a promising core for efficient D-A-D type HTMs towards PSCs. Graphical abstract Image 1 Highlights • Novel D-A-D types HTMs with different acceptor cores were reported. • Acceptor core of the HTMs greatly influences the performance of the PSCs. • DT-2 based PSC obtains a power conversion efficiency of 15.77%. • DT1-2 exhibit better conductivity and hole mobility than spiro-OMeTAD. [ABSTRACT FROM AUTHOR]

Abstract: Three novel metal-free organic dyes with dihydro-5H-dibenzo[b,f]azepine as a donor and cyanoacrylic acid as an anchoring unit were designed as an innovative linear skeleton of D–D–π–A type of organic dyes. The conversion efficiency of the derived dye-sensitized solar cells is moderate. Among them, the dye with a hydroxy group as an additional anchoring moiety exhibited the highest UV–Vis absorption with a maximum molar extinction coefficient of 24,136 M−1 cm−1 at λ max = 458 nm and the best photovoltaic performance with an overall power conversion efficiency of 4.88%, while the dye with a carboxy group as an additional anchoring moiety exhibited the lowest conversion efficiency (4.52%). The results show that the dye loading on the film and photovoltaic performance of the dyes were influenced by the additional anchoring units. [Copyright &y& Elsevier]