Sect and House in Syria: History, Architecture, and Bayt Amongst the Druze in Jaramana

This paper explores the connections between the architecture and materiality of houses and the social idiom of bayt (house, family). The ethnographic exploration is located in the Druze village of Jaramana, on the outskirts of the Syrian capital Damascus. It traces the histories, genealogies, and politics of two families, bayt Abud-Haddad and bayt Ouward, through their houses. By exploring the two families and the architecture of their houses, this paper provides a detailed ethnographic account of historical change in modern Syria, internal diversity, and stratification within the intimate social fabric of the Druze neighbourhood at a time of war, and contributes a relational approach to the anthropological understanding of houses

8.7% Power conversion efficiency polymer solar cell realized with non-chlorinated solvents

The use of environmental friendly solvents for the fabrication of solution processed organic photovoltaics is a key issue to scale up the technology. Nowadays however, toxic and harmful chlorinated solvents are largely used in polymer solar cell laboratory research . In this work we successfully reached high solubility and miscibility of the low band gap polymer Poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl]] (PBDTTT-E-F, commonly known as PTB7), blended with [6,6]-Phenyl-C71-butyric acid methyl-ester ([70]PCBM fullerene derivative) in a non-chlorinated solvent (Dimethylbenzenes also known as Xylenes). We studied the solar cells realized depositing blend solutions based on various Xylenes (ortho, para and an isomeric mixture from technical grade) achieving high power conversion efficiencies up to 8.7%

A comparative study of organic photodetectors based on P3HT and PTB7 polymers for visible light communication

Visible light communication (VLC) is a promising candidate to face the bandwidth limitation problems of traditional radio communication system. The use of a light emitting diode (LED), directly modulated, as a transmitter of the wireless telecommunication link permits the installation of VLC-based systems in practically all human-attended settings (home, office, markets). However, a drawback of VLC systems remains the receiver side, due to the lack of photovoltaic devices for this specific application. Organic electronics based on solution processed technologies has the great potential to be applied in VLC systems, building effective, scalable and low-cost photodetectors. We have investigated the effect of the device architecture on optical and electrical device performance, using both P3HT:PCBM and PTB7:PC70BM bulk-heterojunction active layers. We have established that both materials and structures could affect greatly the device properties, and we have provided an analytical representation of the spectral matching between light source and detector. In particular, the most promising device, based on a P3HT:PCBM blend, has demonstrated high performance, especially using an inverted structure. In this configuration, a device cut-off frequency of ~1.0 MHz has been achieved, paying the way to organic photodetector application on VLC-based telecommunication systems in 5G scenarios

Fluoro-functionalization of vinylene units in a polyarylenevinylene for polymer solar cells

A low band-gap copolymer PDTBTFV alternating bis-thienyl-(bis-alkoxy)-benzothiadiazole blocks with difluorovinylene units and its non-fluorinated counterpart PDTBTV have been synthesized and characterized as donor materials in bulk heterojunction (BHJ) solar cells with PCBM as the acceptor. The solar cells with the fluorinated polymer show better photovoltaic performances than those recorded with the non-fluorinated material. Comparative spectroscopic and computational studies, together with morphological, electrical and optical characterization of thin films, have been carried out to shed light on the reasons for the improvement of performances as induced by the double bond fluorination. Our study introduces the fluorinated double bond as a new conjugated unit in donor polymers for BHJ solar cells