Rafik O. Loutfy

Performance improvement for solution-processed high-mobility ZnO thin-film transistors

The fabrication technology of stable, non-toxic, transparent, high performance zinc oxide (ZnO) thin-film semiconductors via the solution process was investigated. Two methods, which were, respectively, annealing a spin-coated precursor solution and annealing a drop-coated precursor solution, were compared. The prepared ZnO thin-film semiconductor transistors have well-controlled, preferential crystal orientation and exhibit superior field-effect performance characteristics. But the ZnO thin-film transistor (TFT) fabricated by annealing a drop-coated precursor solution has a distinctly elevated linear mobility, which further approaches the saturated mobility, compared with that fabricated by annealing a spin-coated precursor solution. The performance of the solution-processed ZnO TFT was further improved when substituting the spin-coating process by the drop-coating process.

ZnO field-effect transistors prepared by aqueous solution-growth ZnO crystal thin film

A ZnO thin-film transistor (TFT) with a channel layer formed via aqueous solution-growth at low temperature is demonstrated. This ZnO thin-film semiconductor has a well-controlled crystalline form, exhibiting n-channel, enhancement-mode behavior with a channel mobility as large as 0.56 cm2 V−1 s−1. Low-cost, superior transistor characteristics and low-temperature processing makes ZnO TFT attractive for flexible electronics on temperature sensitive substrates.

A simple parallel tandem organic solar cell based on metallophthalocyanines

A simple parallel tandem solar cell based on a combination of Zn-phthalocyanine (Pc) and ClInPc has been fabricated and characterized. Compared to a traditional series tandem cell, parallel tandem cells eliminate the need for a semitransparent recombination layer, reducing the complexity of device fabrication while still providing an excellent increase in device performance. Results show a realized broadening of the spectral response and enhancement of the external quantum efficiency as a result of the complementary absorption profiles of ZnPc and ClInPc in the near infrared region. Introduction of a blended ClInPc:C60 layer is shown to more than double the power conversion efficiency of a standard ZnPc/C60 bilayer device (PCE=0.86%). The enhanced performance of the parallel tandem (PCE=1.81%) arises from an increase in both the open circuit voltage and the short circuit current.

Blend composition study of poly(3,3‴-didodecylquaterthiophene)/[6,6]-phenyl C61 butyric acid methyl ester solution processed organic solar cells

Photovoltaic devices made from blends of poly(3,3‴-didodecylquaterthiophene) (PQT-12) and [6,6]-phenyl C61 butyric acid methyl ester have been fabricated and characterized. By varying the polymer loading in the blend, an optimal power conversion efficiency (PCE) of 0.70% has been achieved for a blend consisting of 15 wt % PQT-12, which is an order of magnitude higher than the PCE for a 50 wt % blend. The apparent reason for the large difference is the fact that blends with higher PQT-12 loading are transport limited, with much larger hole-to-electron mobility ratios.

The role of technology transfer offices in growing new entrepreneurial ecosystems around mid-sized universities

The role of universities has evolved from its traditional focus on education and research to active participation in regional economic development. Technology transfer offices (TTOs) were created at Canadian universities to help regulate and monetise the transfer of knowledge created by the university researchers to the marketplace. In this paper, we examined the role TTOs can play in developing a new entrepreneurial ecosystem around mid-sized research universities, based on the perceptions and expectations of the key stakeholders, involved in the technology transfer process, about the role of TTOs, and if their role can help in developing entrepreneurial culture in their universities. We found that the ability of TTOs to effectively support the commercialisation of university research results is related to the existence of an entrepreneurial culture in the university. If the culture and an entrepreneurial ecosystem do not exist, the role TTOs can play is more limited to its well-established facilitation role. Our findings confirm that TTOs can play a critical role in coordinating different bottom-up initiatives to promote entrepreneurship, and in attracting and integrating new external resources to the university.

Poor confinement of e-h recombination zone in blue oleds

The possibility of making large light-emitting area with low cost has stimulated the research work on organic-based light-emitting devices (OLEDs). OLEDs with emission color covering almost the entire visible range have been realized. This was achieved by simultaneously synthesizing new materials and optimizing the device structure itself by adding/getting rid of different layers. Recently, OLEDs performance has improved and has become adequate for many display applications. However, the main problem still to be solved, concerns the short lifetime of the devices. Surprisingly, there are only few fundamental works on the degradation mechanisms of OLEDs. The mechanisms behind the light decay and the color shifts, especially for blue colour, are still not fully understood. Earlier studies have suggested that the poor balance between the number of electrons and holes in the emitting layer, is one of the main factors in limiting the lifetime of the device.

Energy transfer and cyclopentenone

The rate constant of 6·1 × 105M–1 sec–1 for quenching of benzophenone emission by cyclopentenone requires the triplet energy of cyclopentenone to be in the range of 73–74 kcal/mole.