Karl Wolfgang Böer papers

"After retiring from all official duties at the university, I feel it to be my obligation to devote all my efforts, together with my former students, colleagues and friends, to build on the foundation we created, and extend our influence to a much broader world in making the change from the fossil to a solar world a reality." - Karl Wolfgang Böer, 2014

Physicist, inventor, university professor, and solar energy pioneer Karl Wolfgang Böer was born March 23, 1926, in Berlin, Germany. He became a naturalized American citizen in August 1972. Böer was educated at Humboldt University in Berlin (Diploma, Physics, 1949; Doctorate, Physics, 1952, Dr.rer.nat.habil. State Physics, 1955), where he also taught in Physics from 1950-1958. At Humboldt University, also taught in the II Physics Department and from 1958 to 1961 in his own IV Physics Department. Böer formed and directed a research team, which became a section of the II Physics Department in 1951 with eight scientists. In 1958, Humbolt University created the IV Physics Department for him, which he directed until 1961, when the group had grown to 26 scientists and 23 support personnel.

Upon completion of his doctoral degrees, and in addition to his academic position at Humboldt, Böer founded and became director of the Section of Dielectric Breakdown of the German Academy of Science in Berlin. The laboratories included facilities to grow and analyze cadmium sulfide (CdS) single crystals, optical and electrical laboratories, a magnetic laboratory (40kG/8cm-3), a high pressure facility (20kbar with optical windows), and x-ray, emission spectroscopy, and high vacuum and low temperature facilities. The shops included mechanical (for metal and wood), glass, and electronic shops.

Böer's decision to immigrate to the United States was prompted by the construction of the Berlin Wall, an event that took place while Böer was attending an international scientific conference at Cornell University. Two weeks later he received an invitation to New York University for a guest professorship at the Physics Department and began thereafter his career at the University of Delaware. Böer began his career at the University of Delaware as an associate professor of physics in 1962. In 1965 he became professor of physics; in 1971, professor of physics and engineering; and in 1993, distinguished professor of physics and solar energy.

With a vision of solar energy as a supply source for residential energy and a means to reduce American dependence on foreign oil imports, Böer anticipated issues of the energy crisis of the mid-1970s and founded the Institute of Energy Conservation (IEC) at the University of Delaware in 1972. He served as its director and chief scientist from 1972-1975. Under Böer's direction, the IEC grew from a small research and development group into an internationally renowned research facility named by the U.S. Department of Energy as one of only two Research and Educational Institutes of Excellence in the United States. IEC was an important training ground for many of the individuals who have contributed to advances in photovoltaic technology for delivery of solar energy. In the introduction to a special issue of Progress in Photovoltaics celebrating IEC's 25th anniversary in 1997, Birkmire and Hegedus credited Böer with recognizing the potential of thin film photovoltaic cells coupled in hybrid configuration with thermal collectors to also reduce the solar cell temperature and thereby its collection efficiency. This was a clean and inexpensive means to deliver solar energy. Böer obtained funding from the National Science Foundation, electric power utilities, and the University of Delaware Board of Trustees to establish the IEC. This pioneering endeavor predated the first oil embargo, as well as the establishment of the U.S. Department of Energy and the Solar Energy Research Institute (SERI), both formed in 1977.

Research during the early years at IEC focused on increasing the conversion and delivery efficiency of copper sulfide/cadmium sulfide(Cu2S/CdS)used in thin film solar cells. In 1972, Böer and a team of experts proposed Solar One, the first solar house, to harvest solar energy in a total system approach. The proposal was developed with a team of experts, including Professor Maria Telkes, formerly of MIT, Kudrel Seluck from the University of Minnesota, several of his students and architects. The experimental house, with solar-generated heat and electricity, was built in 1973 at the University of Delaware with support from Delmarva Power and Light Company.

The Solar One House of the University of Delaware was the first systems hybrid house in the world to convert sunlight into electricity and heat through the same solar panels that are incorporated into the roof structure and not deployed on top. The heat is extracted through air-ducts and conducted into the basement where it is stored as heat of fusion in sodium sulfate decahydrate-eutectic (melting at 125o F) filled cylinders and conducting to the rooms for heating in the winter. During clear summer nights the radiation coolness from the roof panels is also conducted into another eutectic salt (melting at 60o F) bin in the basement for cooling the rooms in the summer. The center Window of the living area had a Thrombe wall as a concrete block behind the window to store heat in the winter and distribute it evenly through the adjacent living space. All heat ducts were controlled electronically by louvers from a central control panel with inputs of time, outside and room temperature. The refrigerator in the kitchen had an air-duct to the roof to vent the hot air out from behind to the roof in the summer. A separate battery storage bin was built aside of the house for load leveling of the harvested electric energy, a feature that was decades ahead of its time. The Solar One house was designed using state-of-the-art passive house features, such as super-insulation of outside walls and ceilings; all essential windows were pointing south; the south windows had a proper overhang to protect from direct summer sunshine entry. The house was immediately recognized by the world press as a pioneering breakthrough for solar energy utilization and was open to visitors with more than 100,000 in the first year. It was featured in most of the international science and technical journals and listed as historical building by the US Department of Energy.

Parallel to development of IEC, Böer was involved in creating Solar Energy Systems (SES), Inc., a private company and subsidiary of Shell Oil Company, in contract with the University of Delaware and IEC. Böer served initially as chairman of the board (1972-1981) and chief executive officer (1972-1975); he later served as chief scientist (1975-1985). The purpose of the company was to produce solar energy conversion hardware, beginning with Cu2S/CdS solar cells capable for mass fabrication. By 1985, SES, Inc. had a total of 450 employees of which were 34 research scientists, with a complete instrumented research and analysis laboratory including SIMS, SAM, several electron microscopes for transmission and surface visualization, ultra-vacuum equipment for epitaxial growth, micro-chemical laboratories for analytical and synthetic research. SES also had semi-automatic production equipment for three-shift solar panel production with an 120 sqft Vacuum chamber with pre-vacuum entry and exit chambers to permit semi-continuous vacuum deposition.

In 1975, Böer returned to a fulltime research and teaching position and began advising the University's president on long term projects. In 1993 he was named Distinguished Professor of Physics and Solar Energy. He eventually retired from the University of Delaware in 1994 as Distinguished Professor Emeritus of Physics and Solar Energy after receiving many awards for teaching and research. In 1998, the University presented Böer with its Medal of Distinction. In 2012, he received the doctor honoris causa degree from the Technical University Berlin.

Böer's expertise in solar cells, solary energy systems, solid state physics, and electronic transport in solids is internationally recognized. He holds 28 patents in solid state technology, authored over 350 articles on solid state physics and engineering, and on solar energy conversion. He is the author of seven books, His Survey of semiconductor Physiscs's first volume is treasured as the "Bible of semiconductor physics" and praised by Van Nostrand Reinhold editors as the most comprehensive book of the field ever written by a single author. With over 3,900 pages in two volumes, the third edition is titled Handbook of Semiconductor Physics, co-authored with Professor Udo Pohl, Technical University Berlin. Other books are the Handbook of Thin-Film Solar Cells, Introduction into Space Charge Effects in Semiconductors, and Field- and Current inhomogeneities in semiconductors, all from Springer Verlag, Berlin. Böer has edited or co-edited twelve additional books or conference proceedings. Böer was the founding editor of physica status solidi: the International Journal of Solid State Physics, and edited Solar News and Views in Solar Age, the Journal of Solar Energy Materials, and the editor-in-chief and founder of Advances in Solar Energy. He has received the highest honors of his profession, including election as a fellow of the American Physical Society (1965), fellow of the American Solar Energy Society (ASES, 2000), fellow of the Institute of Electric and Electronic Engineers (IEEE, 2001), and fellow of AAAS (2012).

Throughout his career with the University of Delaware's physics and engineering departments and the IEC, Böer worked on many projects relating to the research of the defect structure of CdS single crystals and the optical and photoelectric properties. He concentrated his main interest on further investigation of high-field domains (now called Böer domains) which he discovered with his team in Berlin before emigrating to the United States. In America, he developed methods for using such domains to unambiguously measure electron density and electron mobilities as a function of high electric fields and discovering the dependence of the work function of CdS with a variation of optical excitation. His most important results were the explanation of a decade-long puzzle, why a very thin layer of CdS on top of a CdTe thin-film solar cell causes its solar conversion efficiency to increase by a factor of two from 8% to 16%. He proved that his Böer domains limit the field at the critical pn-junction of the solar cell to 60 kV/cm, i.e., well below tunneling, and therefore eliminate junction leakage.

Mainly at IEC and SES, In.c, Böer worked on many projects relating to the development and production of solar cells and solar energy conversion. These projects were funded by agencies such as the Department of Energy (DOE), the National Research Energy Laboratory (NREL), the Solar Energy Research Institute (SERI) at DOE, the United States military, NASA, and private corporations. As evidenced in this collection, Böer maintained close contact with the emerging fields of solar energy and energy conservation by attending conferences, making public addresses, reviewing and refereeing academic publications, and serving as a consultant to industries and governments. During the 1970s, he had several government assignments on national energy panels. He was a member of the White House Office of Science and Technology Energy Assessment Panel (1972), the National Advisory Board in Solar Conservation Research (1975-1977), and a member of U.S. Senator William Roth's Delaware Energy Task Force (1974-1975). Additionally, Böer served the National Science Foundation several times, chairing the CdS Solar Cell subpanel (1973) and the Solar Heating Systems subpanel (1973).

In addition to his duties at the University of Delaware, IEC, and SES, Böer worked with various groups and organizations dedicated to the development of solar energy. Böer was an active member of the American Section of International Solar Energy Society (ISES), a professional organization that advanced the use of solar energy through the gathering and dissemination of information related to renewable energy sources. In 1976 Böer was elected to become the president of the American Section of ISES and created a professional office to incorporate it as the American Solar Energy Association (ASES). He also created its own publication office with Solar Today as its bimonthly journal and the Advances of Solar Energy as a yearly book with invited authors only. His first international solar energy conference together with the Canadian solar energy society was for the first time economically successful and published the first proceedings available to all conference participants. With Pergamon Press purchasing the surplus volumes, this created a substantial profit for ASES. After his tenure as president, Böer went on as the treasurer and director of the publication office. The society went from substantial financial problems before to a well-funded society as Böer retired from his office in 1993. ASES opened an office at the University of Delaware in 1978, and eventually became a main office for the organization's publication projects.

In 1995, Böer was named to the advisory board of WISTA, a Science and Technology Center in Berlin-Adlershof, serving as the group's U.S. Representative. Delegates from WISTA toured the United States in order to promote greater technological, educational, and industrial cooperation between the U.S. and Berlin-Adlershof.

In 1987, the University of Delaware established the Karl W. Böer Solar Energy Medal of Merit in Böer's honor. The Award was directed by Dr. Stanley Sandler, Chemical Engineering, (1992-1996); Dr. Gerard Mangone, Maritine Law, (1996-1999); Dr. Robert Birkmyre, Director IEC (2000-2009); Dr. George Hadjipanayis, Physics Department (2010-2013); and Dr. Michael Klein, ISE Lab (2014-present). The candidate is suggested by a letter from the nominator and supported by six letters from experts in the field. The package is then sent to a committee consisting of ten referees, including Ralf Böer, Chair; the presidents or chosen delegates of ASES, ISES, IEEE, NREL, DOE, APS, AChES, ASEE, and AMCE. The Karl W. Böer Foundation is a 501(c) foundation under the treasurer of the University of Delaware with $380,000 original donation that has increased to $1.3 million. The Award is given biannually in a two-day event starting with a dinner given by Renate Böer for the Awardee and distinguished guest on the first day, followed by the presentation of the medal by Böer and the financial part of the Award in form of a check by the University of Delaware president, and the presentation by the Awardee on his work that let to the Award. A black-tie dinner at the University president's home concludes the celebration.

Former President Jimmy Carter was the first recipient of the award in 1993, recognized for his work in focusing the word's attention on solar energy. President Carter installed solar panels on the White House and declared that global solar energy conversion is serious and deserving of broad based research, development and industry attention. Honorees of the Karl W. Böer Solar Energy Medal of Merit receive a bronze medal and a $60,000 stipend. Later awards were given to the following:

1995: to Dr. David Carlson, USA, who invented the first Thin-Film amorphous Silicon Solar Cell with 5% Efficiency, leading to commercial interest.

1997: to Prof Adolf Götzberger, Freiburg Germany: who demonstrated with the first Solar PV/hydrogen House a self-contained operating system with energy storage und use of hydrogen for heating and cooking as well as regenerating electric energy via fuel cells at night.

1999: to Dr. Stanford Ovshinsky, USA: for breakthrough in large scale Commercialization of his improved Amorphous Silicon solar cell with 12% efficiency and >15 year life expectancy.

2001: to Prof Allen Barnett, USA: who commercialized in large-scale production, thin-slice, material saving, single crystal silicon solar cell panels with 18% efficiency demonstrating the first price breakthrough for private consumers.

2003: to Prof. Martin Green, Australia: who sets the world Record with 23.5% solar conversion efficiency, stimulates production for application with high conversion needs (outer space) and is extremely successful educator with books and some of his students becoming the wealthiest Si-entrepreneurs in China and the next generation Si cell inventors.

2005: to Prof. Yoshihiro Hamakawa, Japan: who is the initiator and leader of the Sunshine Program that advances Japan to a leadership in PV. He also improved in his own research the copper-indium-di-arsenide solar cell in the top ranking of polycrystalline solar cells and made these competitive in the present solar cell market.

2007: to Dr. Lawrence Kazmerski, USA: who is a world authority and leader in progress analysis of every solar cell and panel for NREL certification of performance. He is the leader for selecting the government sponsorship of most promising proposals.

2009: to Dr. Herrmann Scheer, Germany: who as member of the German Bundestag was instrumental of introducing the 50 Eurocent tariff for PV-harvested electric power fed back into the Utility Grid, that permitted Germany to become the world leader with 40% electric power from solar. His initiative spread rapidly to many European countries.

2011: to Prof. Richard Swanson, USA: Stanford professor, who is the inventor of Si-single crystal solar cells with all contacts moved from the sun side to the back of the cell, improving the conversion efficiency by more than 2% and the life expectancy to a century.

2013: to Prof Zhores Alferov, Nobel Laureate, and Prof VlacheslavAndreev, Russia, who invented and further developed multi-layer poly-crystalline III/V solar cells that, on top of each other, converted additional parts of the polychromatic sunlight and herewith increased substantially the use of the solar spectrum into electric power.

With these Awardees, the Karl W. Böer Solar Energy Award has become the most prestigious award for the global solar energy community. The proposed awardees have presently a waiting list for an average of five years.

Introduction to Special Issues of Progress in Photovoltaics: The Thin Film Photovoltaic Symposium Commemorating the 25th Anniversary of the Institute of Energy Conversion at the University of Delaware.Editors: Robert W. Birkmire and Steven S. Hegedus. Newark, Del.: IEC, University of Delaware, 1997."Karl Böer." The Complete Marquis Who's Who. Marquis Who's Who, 2003. Reproduced in Biography Resource Center. Farmington Hills, Mich.: The Gale Group, 2003. "Karl Böer." Who's Who in Technology. Detroit: Gale, 1989. 6th ed. Okonowicz, Ed. "Karl W. Boer appointed to German scientific board."UpDate. Newark, Del.: University of Delaware. 8 February 1996. 1-3.Additional biographical information supplied by Dr. Böer, e-mail to the Library, November 10, 2014.

EDUCATION:

• 1955 Dr. rer. nat. habil. Solid State Physics
• 1952 Dr. rer.nat. Physics
• --Special education: Solid State Physics, Electronics
• 1949 Dipl. Phys. Physics (Summa Cum Laude)
• --General education: Chemistry, Physics,Mathematics
• --Languages: English, German (fluent), French(marginal)

EMPLOYMENT HISTORY:

• 1949-1961 Humbolt University, Berlin
• --1949-1952 Assistant
• --1952-1955 Oberassistant
• --1955-1958 Docent
• --1958-1961 Professor with full teaching permission
• --1961 Professor with professorial chair



• 1955-1961 German Academy of Science, Berlin
• --Founder & Director of Section of Dielectric Breakdown



• 1962-1994 University of Delaware
• --1962-1965 Associate Professor of Physics
• --1965-1971 Professor of Physics
• --1971-1994 Professor of Physics & Engineering
• --1972-1975 Founder & Director of Institute of Energy Conversion
• --1975-1982 Chief Scientist of the Institute of Energy Conversion
• --1975-1998 Advisor to the President
• --1995 Distinguished Professor of Physics and Solar Energy
• --1998 Distinguished Professor of Physics and Solar Energy, emeritus



• 1972- SES, INC.
• --1972-1975 Chairman of the Board & Chief Executive Officer
• --1972-1981 Chairman of the Board
• --1975-1985 Chief Scientist



• 1955-pres Editorship
• Fortschritte der Physic
• --1955 Editor
• physica status solidi: International Journal of Solid State Physics
• --1960-1961 Founder & Editor-in-chief
• --1970-pres Editor (Series A)
• Solar News and Views in Solar Age
• --1978-1981 Editor
• Journal of Solar Energy Materials
• --1979- Editor
• Advances in Solar Energy
• --1991 Co-founder
• --1991-2003 Editor-in-chief

VISITING PROFESSORSHIPS:

• 1961-1962 New York University
• 1965 Stanford University
• 1976-1977 Technical University, Berlin, Germany
• 1977 University of New South Wales, Austraila
• 1979 Max Planck Institute for Solid State Physics, Stuttgart (Germany)
• 1994-1995 Paul Drude Institute, Max Planck Gesellschaft, Berlin and Technical Universtiy, Berlin

PROFESSIONAL SOCIETIES:

• American Section of the International Solar Energy Society
• --1969- Member
• --1974 Director
• --1976-1977 Chairman
• --1978 Secretary
• --1978-1981 Director of Publications
• --1978 Chair, Publications Committee
• --1976-1980 Chair, Physics Division
• --2001 Fellow



• American Solar Energy Society
• --1975 Chairman and Founder
• --1976-1977 Chairman



• Mid-Atlantic Solar Energy Association
• --1977 Director



• American Physical Society
• --1962-1964 Member
• --1964-pres Fellow



• Institute of Electric and Electronic Engineers
• --1972-1999 Senior Member
• --2000 Fellow



• Electro-Chemical Society
• --1970 Member
• --1976 Director in Energy Group



• Sigma Pi Sigma, Sigma Chi, honor societies, 1962-



• Delaware Academy of Science, 1962-



• AASS
• --1976 Member
• --1978- Representative of AS of ISES in Physics
• --2002- Fellow

SCIENTIFIC ACHIEVEMENT SUMMARY:

• 1952 First observed dc electroluminescence in single crystals



• 1953 First experimental evidence of Coulomb-repulsive traps



• 1954 Evidence of field excitation of trapped carriers in CdS single crystals



• 1956 Developed a new method to analyze systems of non-linear differential equations



• 1959 Discovered high-field domains (field instabilities in homogenous semiconductors)



• 1959 First description that High-field domains are expected whenever the mobility decreases stronger than linearly with the electric field



• 1959 First experimental observation of Franz-Keldysh effect



• 1960 Developed stable ohmic contacts to CdS



• 1960 Proof of artificial initiation of high-field domains from a virtual (shadow-) cathode



• 1961 Developed electro-optical analysis to measure field inhomogeneties



• 1962 Proposed Bose-Einstein condensation of Excitons



• 1963 Introduced field-of-direction analysis to discuss solution of transport and Poisson-quations



• 1964 Capability to determine the entire n(F) in the field-quenched range by using a virtual cathode with different electron density by variation of the light intensity in the shadow



• 1965 Utilized field and current inhomogeneties producing index of refraction gradients to deflect laser beams



• 1966 Improved substantially the photoelectric properties of evaporated CdS via special recrystallization technique



• 1968 Experimental proof that CdS does turn p-type in high-field domains that are initiated by blocking contacts



• 1968 Introduced stationary high-field domains to determine field dependence of carrier density and mobility



• 1968 & 1975 Developed light induced modulation of optical absorption technique to identify transition anomalies near band edges



• 1969 The use of high-field domains permits the experimental measurement that the work function of blocking electrodes in CdS decreases with increasing optical excitation



• 1969 Proposed model for semiconductivity of glasses



• 1969 Identified initiation of Ovshinsky effect as electrothermal instability



• 1970 Constructed first electrothermal laser beam deflector



• 1971 Proposed a second order phase transition of semi-conducting glasses



• 1972 Utilized high-field domains for sensitive infrared detection



• 1972 Introduced quasi-Fermi level analysis to investigate heterojunctions



• 1972 Proposed Solar One System to harvest solar energy in a total system approach



• 1972 Developed an improved model of the CdS/Cu2S solar cell



• 1972 Improved CdS/Cu2S cell and developed method feasible for mass fabrication



• 1973/1974 Determined that Cd-doping inhomogeneity close to surface is responsible for CdS Class I/II behavior



• 1980 Developed solar cell-equation for non-ideal diodes



• 1981 Developed new kinetic method to measure space charges in junctions



• 1982 Prediction for thermodynamic reasons and measurement that Si solar cell panels cool when electric power is extracted



• 1986 Created a double graphite coated high work-function copper wire electrode for contacts to the Cu2S side of CdS/Cu2S solar cells to avoid copper nuclei formation at the metal/semiconductor interface



• 1987 Eliminated the cause of degradation of CdS-Cu2S solar cells due to copper nodule creation by a) graphite coated contacts and b) elimination of high-field spikes in the Cu2S-coated crystallite crevices, by filling these with appropriate paraphines before the epitaxial growth of the Cu2S on top of the CdS



• 1988 Developed a screw-less deployment that permits sliding-in of solar panels into preset roof structures



• 1994 Inverse delta-doping to improve the open circuit voltage of photo-diodes



• 1995 Use of delta-function doping to understand recombination-induced changes in Voc and FF of solar cells



• 2003 Karl Böer papers, the permanent archive of personal career and work at the Institute of Energy Confersion, opened for research at the University of Delaware Library



• 2008 Prooved that the high-field domain in a 150Å thick layer of CdS on top of the CdTe causes the solar conversion efficiency of CdTe solar cells to increase from 8% to 16%



• 2009 A review of the high degree of utilization of the high-field domain in many fields of semiconductor physics, as discovered in 1958 by Böer and his team, was the reason to rename the effect as the Böer -domain



• 2013 45-Year experimental proof is obtained that a CdS/Cu2S solar cell that is kept during its entire life from its fabrication in 1968 in open air, is still operating an electric motor, on which it is mounted, when illuminated with sunlight. (All previous theories suggest that such cells degrade within three years because of photoelectric degradation in humid air)



• 2014 Model of the Solar One house to be displayed at the entrance hall of the Institute of Energy Conversion, that is surrounded at the wall behind with panels that explains the functionalities of the house, and adjacent, on the wall an operational CdS/Cu2S cell exposed to open air, that starts to rotate when the light above the cell is switched on



• 2015 Karl W. Böer Laboratory for Electrical Battery Solar Energy Storage



• In addition, numerous papers were published with contributions to better understanding of the photoconductivity and defect structure of CdS, of the dielectric breakdown, the electronic noise, photochemical reactions, di-electric after-effects, the influence of atmospheric ambients on photoconductance (all in CdS), photovoltaics (specifically CdS/Cu2S cells), solar energy conversion, the semiconductivity of glasses, blocking and the ohmic contacts, TSC analysis, reaction kinetics in photoconductors, and to the terrestrial utilization of solar energy.