- Email: [email protected]
Photovoltaic and photoactive materials—properties, technology and applications
Solar Energy Materials & Solar Cells 76 (2003) 429–430
Guest editorial
Photovoltaic and photoactive materials— properties, technology and applications This special issue of Solar Energy Materials & Solar Cells was stimulated by a NATO-funded Advanced Study Institute (ASI), on the topic of ‘‘Photovoltaic and Photoactive Materials—Properties, Technology and Applications’’. This subject area is primarily fuelled by substantial worldwide efforts for the utilization of solar energy. Contemporary solar cell technology is dominated by crystalline silicon (c-Si). The annual rate of growth of cell production reached 40% in the year 2000, with around 80–90% of cells being based on c-Si. The current primary goal is to continue this successful development, and to reach a few GWp of installed power production by the end of the present decade. Promising alternatives for solar energy utilization are thin firm technologies involving various new materials. The stimulus for thin film photovoltaic technology development is supplied by the advantages which it offers in: (i) decreasing the amount of expensive semiconductor material required, (ii) using low-cost substrates, and (iii) fabrication of large-area cells and modules. A substantial reduction in the manufacturing cost of solar cells is expected via this approach. Various materials other than c-Si are being considered for the preparation of solar cells. So far, amorphous silicon (a-Si:H), cadmium telluride (CdTe) and copper indium diselenide (CIS) thin film PV technologies have been commercialised. A notably successful technology is that using CIS, where a conversion efficiency of the order of 18% has been reached. Many research laboratories are also studying thin films of amorphous, microcrystalline and porous silicon, trying to resolve basic physical problems. Amorphous silicon has been the subject of long-term research, but the presence of large concentrations of defects and the occurrence of instability processes still constitute barriers to the achievement of an optimised cell efficiency. The realisation of microcrystalline silicon cells of moderate efficiency and good stability has thus opened up a new area of photovoltaic development. Also, an improvement in the efficiency of a single-junction device has been achieved in a tandem structure incorporating a microcrystalline silicon bottom cell located below an a-Si:H top cell, giving an initial efficiency of 13%. Quick industrial realisation has been possible due to the maturity of amorphous silicon technology, including optimisation of the back reflector and transparent conducting oxide front contact, plus the introduction of monolithic integration and effective encapsulation procedures. As an important separate area of interest in the field of photoactive materials, interest in electronically switchable systems is continuously expanding, with many potential new markets and technological approaches. Switchable windows can be used for many applications including architectural, vehicle and aircraft windows, 0927-0248/02/$ - see front matter r 2002 Published by Elsevier Science B.V. PII: S 0 9 2 7 - 0 2 4 8 ( 0 2 ) 0 0 2 5 7 - X
430
Guest editorial / Solar Energy Materials & Solar Cells 76 (2003) 429–430
skylights and sunroofs. They rely on a variety of processes and materials. Conventional glazing offers only a fixed transmittance, with no external control over the energy passing through it. Given the wide range of illumination conditions and glare, dynamic glazing with adjustable transmittance offers a better solution. Applications other than glazing include low-information-content large-area visual displays. The primary objective of the NATO ASI which provided the stimulus for the present issue was to present an up-to-date overview of various current topics of interest in the field of photovoltaic and related photoactive materials. As indicated above, this is a wide-ranging subject area of significant commercial and environmental interest, which involves major contributions from the disciplines of physics, chemistry, materials, electrical and instrumentation engineering, commercial realisation, etc. This is reflected in the range of contributions selected for inclusion in this volume. The ASI was held in Sozopol, Bulgaria, in September 2001, and was directed by Prof. Joe Marshall (University of Wales, Swansea, UK) and Prof. Doriana Dimova-Malinovska (Central Laboratory of Solar Energy & New Energy Sources, Bulgarian Academy of Sciences, Bulgaria). It brought together young scientists and highly experienced lecturers from a suitably diverse range of disciplines and backgrounds. In particular, we thank Prof. Carl Lampert for accepting the invitation to lecture at the ASI, and for his encouragement that it should form the basis of this special issue of Solar Energy Materials & Solar Cells. We hope that the contents will be of value to readers interested in the current status of various aspects of the subject area. If so, it is relevant to note that the full Proceedings of the ASI, comprising detailed contributions by the lecture team plus an extended selection of shorter articles by other participants, will appear as a volume in the NATO Science Series (Kluwer Academic Publishers). We here acknowledge the financing on behalf of the NATO Scientific Committee, which made possible not only the school, but this issue as well. The reliable help of Tatyana Ivanova, a young research collaborator in the Central Laboratory of Solar Energy and New Energy Sources, Bulgarian Academy of Sciences, Bulgaria, is also highly appreciated. We are pleased to note that the timing of this special issue of Solar Energy Materials & Solar Cells coincides with the 25th anniversary of the founding of the Central Laboratory of Solar Energy and New Energy Sources of the Bulgarian Academy of Sciences. We would thus like to dedicate the present issue to this event. K.A. Gesheva and D. Dimova-Malinovska Central Laboratory of Solar Energy & New Energy Sources, Bulgarian Academy of Sciences, Blvd. Tzarigradsko Chaussee 72, 1784 Sofia, Bulgaria Email address: [email protected], [email protected] J.M. Marshall and J.M. Maud Department of Materials Engineering, University of Wales, Swansea, SA2 8PP, UK Email address: [email protected]
Guest editorial
Photovoltaic and photoactive materials— properties, technology and applications This special issue of Solar Energy Materials & Solar Cells was stimulated by a NATO-funded Advanced Study Institute (ASI), on the topic of ‘‘Photovoltaic and Photoactive Materials—Properties, Technology and Applications’’. This subject area is primarily fuelled by substantial worldwide efforts for the utilization of solar energy. Contemporary solar cell technology is dominated by crystalline silicon (c-Si). The annual rate of growth of cell production reached 40% in the year 2000, with around 80–90% of cells being based on c-Si. The current primary goal is to continue this successful development, and to reach a few GWp of installed power production by the end of the present decade. Promising alternatives for solar energy utilization are thin firm technologies involving various new materials. The stimulus for thin film photovoltaic technology development is supplied by the advantages which it offers in: (i) decreasing the amount of expensive semiconductor material required, (ii) using low-cost substrates, and (iii) fabrication of large-area cells and modules. A substantial reduction in the manufacturing cost of solar cells is expected via this approach. Various materials other than c-Si are being considered for the preparation of solar cells. So far, amorphous silicon (a-Si:H), cadmium telluride (CdTe) and copper indium diselenide (CIS) thin film PV technologies have been commercialised. A notably successful technology is that using CIS, where a conversion efficiency of the order of 18% has been reached. Many research laboratories are also studying thin films of amorphous, microcrystalline and porous silicon, trying to resolve basic physical problems. Amorphous silicon has been the subject of long-term research, but the presence of large concentrations of defects and the occurrence of instability processes still constitute barriers to the achievement of an optimised cell efficiency. The realisation of microcrystalline silicon cells of moderate efficiency and good stability has thus opened up a new area of photovoltaic development. Also, an improvement in the efficiency of a single-junction device has been achieved in a tandem structure incorporating a microcrystalline silicon bottom cell located below an a-Si:H top cell, giving an initial efficiency of 13%. Quick industrial realisation has been possible due to the maturity of amorphous silicon technology, including optimisation of the back reflector and transparent conducting oxide front contact, plus the introduction of monolithic integration and effective encapsulation procedures. As an important separate area of interest in the field of photoactive materials, interest in electronically switchable systems is continuously expanding, with many potential new markets and technological approaches. Switchable windows can be used for many applications including architectural, vehicle and aircraft windows, 0927-0248/02/$ - see front matter r 2002 Published by Elsevier Science B.V. PII: S 0 9 2 7 - 0 2 4 8 ( 0 2 ) 0 0 2 5 7 - X
430
Guest editorial / Solar Energy Materials & Solar Cells 76 (2003) 429–430
skylights and sunroofs. They rely on a variety of processes and materials. Conventional glazing offers only a fixed transmittance, with no external control over the energy passing through it. Given the wide range of illumination conditions and glare, dynamic glazing with adjustable transmittance offers a better solution. Applications other than glazing include low-information-content large-area visual displays. The primary objective of the NATO ASI which provided the stimulus for the present issue was to present an up-to-date overview of various current topics of interest in the field of photovoltaic and related photoactive materials. As indicated above, this is a wide-ranging subject area of significant commercial and environmental interest, which involves major contributions from the disciplines of physics, chemistry, materials, electrical and instrumentation engineering, commercial realisation, etc. This is reflected in the range of contributions selected for inclusion in this volume. The ASI was held in Sozopol, Bulgaria, in September 2001, and was directed by Prof. Joe Marshall (University of Wales, Swansea, UK) and Prof. Doriana Dimova-Malinovska (Central Laboratory of Solar Energy & New Energy Sources, Bulgarian Academy of Sciences, Bulgaria). It brought together young scientists and highly experienced lecturers from a suitably diverse range of disciplines and backgrounds. In particular, we thank Prof. Carl Lampert for accepting the invitation to lecture at the ASI, and for his encouragement that it should form the basis of this special issue of Solar Energy Materials & Solar Cells. We hope that the contents will be of value to readers interested in the current status of various aspects of the subject area. If so, it is relevant to note that the full Proceedings of the ASI, comprising detailed contributions by the lecture team plus an extended selection of shorter articles by other participants, will appear as a volume in the NATO Science Series (Kluwer Academic Publishers). We here acknowledge the financing on behalf of the NATO Scientific Committee, which made possible not only the school, but this issue as well. The reliable help of Tatyana Ivanova, a young research collaborator in the Central Laboratory of Solar Energy and New Energy Sources, Bulgarian Academy of Sciences, Bulgaria, is also highly appreciated. We are pleased to note that the timing of this special issue of Solar Energy Materials & Solar Cells coincides with the 25th anniversary of the founding of the Central Laboratory of Solar Energy and New Energy Sources of the Bulgarian Academy of Sciences. We would thus like to dedicate the present issue to this event. K.A. Gesheva and D. Dimova-Malinovska Central Laboratory of Solar Energy & New Energy Sources, Bulgarian Academy of Sciences, Blvd. Tzarigradsko Chaussee 72, 1784 Sofia, Bulgaria Email address: [email protected], [email protected] J.M. Marshall and J.M. Maud Department of Materials Engineering, University of Wales, Swansea, SA2 8PP, UK Email address: [email protected]