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Organic solar cells have attracted academic and industrial interests due to the advantages like lightweight, flexibility and roll-to-roll fabrication. Nowadays, 18% power conversion efficiency has been achieved in the state-of-the-art organic solar cells. The recent rapid progress in organic solar cells relies on the continuously emerging new materials and device fabrication technologies, and the deep understanding on film morphology, molecular packing and device physics. Donor and acceptor materials are the key materials for organic solar cells since they determine the device performance. The past 25 years have witnessed an odyssey in developing high-performance donors and acceptors. In this review, we focus on those star materials and milestone work, and introduce the molecular structure evolution of key materials. These key materials include homopolymer donors, D-A copolymer donors, A-D-A small molecular donors, fullerene acceptors and nonfullerene acceptors. At last, we outlook the challenges and very important directions in key materials development., Funding Agencies|National Natural Science Foundation of ChinaNational Natural Science Foundation of China [51773045, 21772030, 51922032, 21961160720]

The organic–inorganic halide CH 3 NH 3 PbI 3 (MAPbI 3 ) has been the most commonly used light absorber layer of perovskite solar cells (PSCs); however, solution-processed MAPbI 3 films usually suffer from random crystal orientation and high trap density, resulting in inferior power conversion efficiency (PCE) with open circuit voltage (V oc ) being typically below 1.2 V for PSC devices. Herein, for the first time an imidazole sulfonate zwitterion, 4-(1H-imidazol-3-ium-3-yl)butane-1-sulfonate (IMS), is applied as a bifunctional additive in regular-structure planar heterojunction PSC devices to regulate the crystal orientation, yielding highly ordered MAPbI 3 film and passivating the trap states of the film. Such a dual effect of IMS is fulfilled via coordination interactions between the sulfonate moiety of IMS with the Pb2 + ion and the electrostatic interaction between the imidazole of IMS with the I – ion of MAPbI 3 . As a result, under a optimized IMS doping ratio of 0.5 wt%, the PSC device exhibits a significant increase in PCE from 18.77% to 20.84%, with suppressed current–voltage hysteresis and promoted ambient stability. Moreover, a high V oc of 1.208 V is achieved under a higher IMS doping ratio of 1.2 wt%, which is the highest V oc for regular-structure MAPbI 3 planar PSC devices based on TiO 2 electron transport layer. © 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

It has been well documented that cattle raised on pasture are slow in weight gain when compared to those fed with grain. Inflammation in the digestive system commonly caused by pasture-transmitted gastrointestinal (GI) nematode parasites that could negatively impact feed conversion has never been compared in cattle raised with no pasture exposure (NPE, uninfected), limited pasture exposure (LPE, exposure until weaning), or continuous pasture exposure (CPE, life time exposure). In the present study, the abomasal mucosal immune responses and inflammation of LPE and CPE cattle were investigated. Our results indicate that CPE cattle displayed inflamed abomasa with enlarged draining lymph nodes, the presence of Ostertagia ostertagi larvae and higher levels of Ostertagia-specific antibodies in circulation. The level of B cells was elevated in the abomasal mucosa in the presence (nodular) or absence (non-nodular) of Ostertagia-specific pathology, where B cells were 4-fold higher in the nodular mucosa. Foxp3+ CD4T cells were also noticeably elevated in both the abomasal mucosa and blood, but were only slightly higher in non-nodular mucosa than in the nodular mucosa of CPE animals. In contrast, LPE animals presented no enlargement of abomasal draining lymph nodes and exhibited little to no immune cell infiltration in the abomasal mucosa. Further, CPE animals had higher numbers of mucosal mast cells when compared to LPE animals, though mucosal mast cells were high in all animals. Overall, CPE cattle displayed significantly higher levels of inflammation and pathology in their abomasa and may explain in part slowed weight gain relative to LPE animals. The results of this study emphasize the need for GI nematode parasite control in CPE animals and development and application of vaccines which are compatible with the organic cattle production system.

Solution processed thin film photovoltaic devices are one of the most promising renewable energy sources. Organic solar cells have been intensively studied due to their advantages of light-weight, flexibility and low-cost materials and manufacturing. The organic-inorganic hybrid perovskite materials have recently shown great potential application in solar cells. The PCE increased dramatically from 3.8% in 2009 to a certified efficiency of 20.1% in 2014. In this dissertation, we focus on the efficiency enhancement for solution processed organic and organic-inorganic solar cells. In Chapter 2, I demonstrated that the crystallinity of the ferroelectric polymer P(VDF-TrFE) at the organic active layer/ electrode interface plays a critical role in the efficiency enhancement of organic solar cells. Then, The ferroelectric P(VDF-TrFE) nanocrystals was synthesized and successfully applied in the low band gap polymers. A high efficiency of 6.8% was achieved in the PCDTBT:PCBM system. Another small polar molecule, TPACA, was also applied to increase the efficiency of organic solar cells. In Chapter 3, I developed a universal approach of solvent fluxing to fabricate graded bulk heterojunction (BHJ) polymer:fullerene films to increase the device efficiency. The solvent fluxing process can extract part of the fullerene inside the BHJ film to the top surface to form graded BHJ. The PCE of the devices after solvent fluxing is increased by 15%–50% compared with the control devices without solvent fluxing. In Chapter 5, a two-step spin coating approach was developed to fabricate the continuous and compact organolead trihalide perovskite (OTP) films. The average PCE of methylammonium lead iodide (MAPbI3) perovskite devices reached 14.5% and 85% of the devices had efficiency above 14%. In Chapter 6, I discovered that the solvent annealing can be used to increase the grain size and crystallinity of the perovskite films. The highest device efficiency reached 15.6%, and device efficiency

Reduced graphene oxide (RGO) has been covalently functionalized with porphyrin moieties by two methods: A straightforward Prato reaction (i.e. a 1,3-dipolar cycloaddition) with sarcosine and a formyl-containing porphyrin, and a stepwise method that involves a 1,3-dipolar cycloaddition to the RGO surface using 4-hydroxybenzaldehyde, followed by nucleophilic substitution with an appropriate porphyrin. The chemical bonding of porphyrins to the RGO surface has been confirmed by ultraviolet/visible absorption, fluorescence, Fourier-transform infrared, and Raman spectroscopies, X-ray powder diffraction and X-ray photoelectron spectroscopy, transmission electron and atomic force microscopy, and thermogravimetric analysis; this chemical attachment assures efficient electron/energy transfer between RGO and the porphyrin, and affords improved optical nonlinearities compared to those of the RGO precursor and the pristine porphyrin.[Figure not available: see fulltext.]

The ability to induce humoral and cellular immunity via antigen delivery through the unbroken skin (epicutaneous immunization, EPI) has immediate relevance for vaccine development. However, it is unclear which adjuvants induce protective memory CD8 T-cell responses by this route, and the molecular and cellular requirements for priming through intact skin are not defined. We report that cholera toxin (CT) is superior to other adjuvants in its ability to prime memory CD8 T cells that control bacterial and viral challenges. Epicutaneous immunization with CT does not require engagement of classic toll-like receptor (TLR) and inflammasome pathways and, surprisingly, is independent of skin langerin-expressing cells (including Langerhans cells). However, CT adjuvanticity required type-I IFN sensitivity, participation of a Batf3-dependent dendritic cell (DC) population and engagement of CT with suitable gangliosides. Chemoenzymatic generation of CT–antigen fusion proteins led to efficient priming of the CD8 T-cell responses, paving the way for development of this immunization strategy as a therapeutic option.