Donor-п-acceptor conjugated copolymers for photovoltaic applications : tuning the open-circuit voltage by adjusting the donor/acceptor ratio

A class of new conjugated copolymers containing a donor (thiophene)−acceptor (2-pyran-4-ylidene-malononitrile) was synthesized via Stille coupling polymerization. The resulting copolymers were characterized by 1H NMR, elemental analysis, GPC, TGA, and DSC. UV−vis spectra indicated that the increase in the content of the thiophene units increased the interaction between the polymer main chains to cause a red-shift in the optical absorbance. Cyclic voltammetry was used to estimate the energy levels of the lowest unoccupied molecular orbital (LUMO) and the highest occupied molecular orbital (HOMO) and the band gap (Eg) of the copolymers. The basic electronic structures of the copolymers were also studied by DFT calculations with the GGA/B3LYP function. Both the experimental and the calculated results indicated an increase in the HOMO energy level with increasing the content of thiophene units, whereas the corresponding change in the LUMO energy level was much smaller. Polymer photovoltaic cells of a bulk heterojunction were fabricated with the structure of ITO/PEDOT/PSS (30 nm)/copolymer−PCBM blend (70 nm)/Ca (8 nm)/Al (140 nm). It was found that the open-circuit voltage (Voc) increased (up to 0.93 V) with a decrease in the content of thiophene units. Although the observed power convention efficiency is still relatively low (up to 0.9%), the corresponding low fill factor (0.29) indicates considerable room for further improvement in the device performance. These results provided a novel concept for developing high Voc photovoltaic cells based on donor-π-acceptor conjugated copolymers by adjusting the donor/acceptor ratio.

Estimating the demand for money in an unstable open economy : the case of the Fiji Islands

In this paper, we estimate Fiji's money demand function for the period 1971-2002 based on the bounds testing approach to cointegration, which is applicable irrespective of whether or not the underlying variables are non-stationary. We estimate models with and without a time trend and for lag lengths ranging from 1-3, but fail to find any evidence for a long-run relationship. Moreover, our structural break analysis suggests that the unstable nature of Fiji's money demand may be due to atypical events, such as coups; the implementation of policies, such as devaluations and value added tax; and the onset of trade liberalisation policies over the last two decades.

Considerations for performing arts organisations in a climate of transition to the open market context in Vietnam

The emergence of a global economy and culture has created a worldwide climate of change since the 1980s. These changes impact on the growth of a national economy and change the significance of sectors in society, for example the service sector, which increasingly accounts for an important part of the economy (Burbules & Torres, 2000). The arts have also been profoundly influenced by social changes, and technological development. While these changes pose new challenges for the arts, most of which struggle for financial viability in an era of globalisation, privatisation and reduced public funding, the developments also open new opportunities for arts companies/artists but require them to possess the capability to identify and adapt to change. This process underlines the necessary new capacities of arts management, arts marketing, arts leaders and artists.

Doi moi - Vietnamese economic reforms in 1986 - provided impetus for change in every sector, resulting in growth of the service sector in Vietnam (UNDP, 2002). Arts organisations in Vietnam found themselves operating in a more competitive environment, forcing them to adjust to this new economic structure. Improved Vietnamese living standards helped to create more demands for a diverse entertainment industry and allowed both the government and individuals to spend more on the arts. A new cultural policy - socialisation (somewhat equivalent to privatisation in Western countries) was implemented in the arts and cultural sector, producing for performing arts organisations (PAOs) as well as a broader cultural milieu in Vietnam, challenges of being self-sustaining but also more autonomy and greater funding diversity. Simultaneously, this led to upgraded artistic standards, improved infrastructure and higher musicians’ salaries; the latter having only experienced slow improvement during the subsidised era.

This paper investigates how social changes affected organisational operations of selected PAOs in Vietnam and Australia. The analysis of how PAOs in each country adjusted to rapid changes will provide experience for learning from each other, particularly for the Vietnamese case. These analyses provide points of discussion, comparison and implications for development of arts management training in Vietnam. Case studies, personal interviews with key participants and policy actors have been used to discern which direction performing arts management should take in order to correspond with Vietnam’s present and future economic situation and its political position in the world.

Designing open-ended problems to challenge preservice teachers' views on mathematics and pedagogy

This study examines preservice elementary teachers' reported experiences of posing open-ended mathematics problems. Responses of 33 students in a mathematics teacher education course were analysed for the strategies participants used, what they learned and the challenges encountered from an opportunity to collect digital images and pose open-ended problems related to those images. Results indicate that preservice teachers reported a shift in the ways they viewed mathematics and how it might be taught. The school curriculum both constrained and provided possibilities for preservice teachers in noticing mathematics beyond the textbook and mathematics classroom. This study adds to our understanding of teaching as a learning practice and the art of posing mathematical problems as a significant aspect of that practice.

Cracking it open

Cracking it Open puts the spotlight on improvisation with live performances by some of Melbourne's leading improvisation artists. Each artist presents a short performance, and then opens the floor for discussion with audience members.

Changes in arts organisations under the open market economy in Vietnam

The paper examines changes in arts organisations in Vietnam under the context of changes in the arts and culture sector in Vietnam and in the world.

Internal and external imagery perspective measurement and use in imagining open and closed sport skills: an exploratory study

This study explored the measurement and use of internal and external imagery perspectives during imagery of open and closed sports skills. Participants  (N=41; male=23; female = 18), ages 14 to 28 (M=19.4 yr.; sD=3.1), who were recruited from undergraduate classes in human movement and physical education, and local sporting teams, completed the Imagery Use Questionnaire and then imagined performing eight common sports skills, four open skills and four closed skills, in a random order. Participants provided concurrent verbalisation during their imagery. Immediately after imagining each skill, participants completed a rating scale and retrospective verbalisation of imagery perspective use. Analysis indicated that the questionnaire gave a general imagery perspective preference but was not a strong predictor of imagery used on specific occasions. The three measures of imagery perspective were equivalent in imagining performing particular skills. Participants experienced more internal imagery than external imagery while imagining the eight sports skills, but there was no significant difference between perspective use on the open and closed skills.