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Rough dense sol-gel-derived titanium dioxide (TiO 2 ) electron-transport layers (ETLs) and smooth organolead halide perovskite (PVK) films for pseudo-planar heterojunction perovskite solar cells (P-PH PVKSCs) were fabricated by a facile one-step dip-coating method. The highly compact TiO 2 ETLs and uniform PVK films endow the device a high power conversion efficiency (PCE) of over 11%, which was nearly identical to that of a reference device (12%) fabricated by conventional spin-coating. Furthermore, the device showed no pronounced hysteresis when tested by scanning the voltage in a forward and backward direction, showing the potential of facile and waste-free dip-coating in replacing of spin-coating for large area perovskite solar cells preparation. Lastly, the hysteresis was compared and discussed and models regarding the abnormal hysteresis, roll-over and current peak phenomena were proposed as well. [ABSTRACT FROM AUTHOR]

An effective and facile surface optimization method is conducted by spin-coating the solution containing Al(NO 3 ) 3 upon compact TiO 2 (c-TiO 2 ) electrode for enlarging the performance of planar perovskite solar cells (p-PSCs). Meanwhile, the influence of Al(NO 3 ) 3 solution concentration on efficiency performance of p-PSCs is also carefully investigated. The study results highlight that a discrete Al 2 O 3 film can be formed on c-TiO 2 electrode to passivate superficial oxygen vacancies defects and create a pleasurable surface topography, alone with high optical transparency. As a consequence, the champion device based on the modified c-TiO 2 (Al-TiO 2 ) via spinning 0.7 wt% Al(NO 3 ) 3 solution drastically yields an enhanced power conversion efficiency of 14.75% as well as enjoys superior device stability compared to its counterpart based on bare c-TiO 2 . Through a further analysis, the fact that Al-TiO 2 can effectively augment the charge collection and abate charge recombination efficiency by the suppression of oxygen vacancy defects at Al-TiO 2 /CH 3 NH 3 PbI 3-x Cl x interface than that of bare c-TiO 2 without modification is unveiled. Those findings provide an insight into the correlation between p-PSCs performance and the microscopic characteristics of c-TiO 2 , and put forward an effective measure to further promote the performance of p-PSCs for their record efficiency. [ABSTRACT FROM AUTHOR]

The power conversion efficiency (PCE) of ternary organic solar cells (OSCs) based on PTB7-Th:PCDTBT:PC 70 BM with good air stability needs to be further improved. We report here 2 min methanol solvent treatment of the active layer of ternary OSCs based on PTB7-Th:PCDTBT:PC 70 BM can significantly boost efficiency up to 9.60%, which exhibits a 30.4% improvement compared to that of 7.36% for the device without methanol solvent treatment. The performance improvement is mainly due to the enhanced light absorption, efficient charge transfer and optimized bulk morphology in the ternary active layer. Meanwhile, the air stability of the methanol solvent treated device can be clearly improved by the removal of residual DIO in the active layer. The PCE of the 2 min methanol treated device could retain 95.4% of the initial value after 7 days of storage in air. Our results indicate that methanol solvent treatment is a simple but effective strategy to boost efficiency and air stability of ternary OSCs based on PTB7-Th:PCDTBT:PC 70 BM. [ABSTRACT FROM AUTHOR]

Ternary bulk heterojunctions (BHJs) are promising candidates that can improve the power conversion efficiencies (PCEs) of organic solar cells (OSCs). In this paper, a ternary OSC with two donors, including one wide bandgap polymer poly[ N -9′-heptadecanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)] (PCDTBT), one low bandgap polymer Poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2- b :4,5- b ′]dithiophene-co-3-fluorothieno[3,4- b ]thiophene-2-carboxylate] (PTB7-Th), and one acceptor [6,6]-phenyl C70 butyric acid methyl ester (PC 70 BM), is fabricated in atmospheric conditions. By incorporating a 20% content of PCDTBT, an optimized PCE of 7.86% for ternary OSC is characterized by a short-circuit current density ( J sc ) of 15.21 mA cm −2 , a fill factor of 69.70% and an open-circuit voltage ( V oc ) of 0.74 V. The V oc values increased steadily from 0.73 to 0.86 V as the increase of PCDTBT fraction, which indicates that the V oc of ternary OSC is not limited by the smallest one of the corresponding binary OSC. We show that the J sc of the ternary OSC is better than those of the binary OSC in virtue of the complementary polymer absorption and cascade energy levels, as well as optimized morphology of the ternary system. Furthermore, the lifetime of the devices with PCDTBT is greatly enhanced. This work indicates that two donors (PTB7-Th/PCDTBT) ternary BHJs system provide a simple and effective method to improve the performance and also the stability of OSCs. [ABSTRACT FROM AUTHOR]

A rapid annealing technique for fabricating perovskite materials via microwave radiation in air condition is presented. A planar-heterojunction perovskite device via microwave radiation within 6 min exhibits an efficiency of 10.29%, compared to 11.08% for a 90 min heating-annealed device in inert atmosphere, which is higher than that (8.04%) of a heating-annealed device in air condition under high humidity (∼60%). We believe that the microwave annealing technique provides a fast and less energy-intensive process for fabricating ideal perovskite active layers for high performance solar cells. [ABSTRACT FROM AUTHOR]

Blue emitters are necessary for achieving full-color displaying OLEDs, however, most blue emitters show low efficiency, short lifetime or serious efficiency roll-off, hindering the development of OLED techniques. In this research, a nonpolar symmetric aggregation-induced emission (AIE) emitter was designed and constructed through facile steps, with the triphenylamine-end, anthracene-spacer and tetraphenylethene (TPE)-center. This emitter exhibited good thermal stability and aggregation-enhanced emission (AEE) characteristics, based on which non-doped blue OLED device was readily fabricated with the maximum external quantum efficiency (EQE) of 2.7% and also with no efficiency roll-off even at 1000 cd m−2, indicative of high efficiency and good stability as fluorescent emitter. Image 1072006 • This emitter with good thermal stability and aggregation-enhanced emission (AEE) characteristics. • Non-doped blue OLED device was fabricated with the maximum external quantum efficiency (EQE) of 2.7%. • Non-doped blue OLED device with no efficiency roll-off even at 1000 cd m−2. [ABSTRACT FROM AUTHOR]