What is Phosolar?

  • Phosolar is a new term for Phosphorescent Solar Energy and the technology surrounding it.1 Phosphorescent Solar Energy is electrical energy derived from a phosphorescent substance placed in sunlight. The electrons of the substance absorb photons of light energy from the sun. The electrons become excited by the photons and leap into a higher orbit around the nucleus of the atom.2 Because they are so far out of their usual orbit, and because they hover for so long in that high orbit, they can, in theory, be harvested as an electrical current.
  • The hovering electrons can also be used as a store of electrical energy - this aspect is being developed through research into methods of keeping the electrons in their high orbit by varying external factors (eg temperature).
  • Due to the fact that phosphorescent materials such as Molybdenum and Molybdenum Disulfide are sensitive to the full spectrum of sunlight, it potentially converts light into electricity at 100% efficiency. This means that multi-layered solar cells become unnecessary.

Thus phosolar offers three technological possibilities:

  • Generating electrons by using substances that respond to a wider range of wavelengths of Sunlight than the traditional Silicon cells and the newer Ruthenium dye-sensitized solar cells;
  • Harvesting the electrons by siphoning them off;
  • Storing the electrons in high orbit, thus creating a de facto battery.
solar panels
The variety of solar panels

What is phosphorescence and how is it different from flourescence?

  • Phosphorescence and fluorescence both involve the absorption of photons of light by electrons. In the case of fluorescence the electrons, which have jumped to a higher orbit, re-emit that photon of light immediately after reaching orbit, thus allowing the electron to descend to its former orbit. Phosphorescence, however, involves electrons jumping to higher orbits and being unable to descend to their former orbit immediately due to lack of opportunity. They thus retain their photon until they find an opportunity to descend, at which time they release the photon of light and then drop back down to their former position. The emission of light therefore occurs over an extended period of time, the length of time depends firstly on the substance and then on the environmental factors.

Examples of substances that phosphoresce:

  • Molybdenum Disulfide and Molybdenum amalgams:
    • Qualities of Molybdenum (Mo): a transition element (number 42); silvery white metal; has a high melting point and is used as a high-temperature lubricant; combined as an alloy with other metals to increase strength and hardness; has high electrical conductivity; resists corrosion; used as a pigment; as a trace element in soil it improves cauliflower growth. It is also found in organisms in an enzyme form (compound form), especially those involved in nitrogen fixation but also in the gut of beetles and in the bodies of humans. In a compound form (as Molybdenum Disulfide [MoS2]), and in some amalgam forms, it is phosphorescent.
  • Strontium Aluminate (doped with Europium)
  • Zinc Sulphide

For how long do substances phosphoresce?

  • Some phosphorescent substances incorporated into manufactured items can now phosphoresce in darkness for 10 hours after being placed in sunlight. This means that phosphorescent solar energy can be available for nearly an entire day. By using the technology of harvesting in combination with the technology of storage Phosolar approaches a round-the-clock phenomenon, although in a very weak form. This potentially puts it into the same competitive field as coal-fired power stations. However, the technology of phosphescent solar energy has yet to be built and tested. The real power of phosphorescent solar energy is during the daytime with the intense power of the Sun directly activating the phosphorescent compound. The night-time potential, however, should not be overlooked and should be continually improved.

What is the efficiency of phosolar?

  • Recent reports from the laboratory indicate that molybdenum organic compounds produce clouds of electrons that remain in orbit for considerable time.3 It may be possible to convert sunlight into electricity at a rate of about 100%. This suggests that phosolar panels would produce about 1 kW per square metre of solar panel.

News from the Laboratory

  • The Australian CSIRO is doing research on organometallic complexes that contain phosphorescent metal atoms complexed into organic plastic polymers in order to manufacture flexible thin-film solar cells. Phosphorescent Iridium is being used in conjugated polymers. Some of this research is about light-to-electricity (Solar Cell) and other research deals with electricity-to-light (OLED) using the same or similar material.5.
  • A European association of scientists and developers called Nanophosolar has received a grant of more than Euros 1.92 million from the European Council to develop phosolar technologies and apply them to solar energy panels, both new and existing types. Their research includes the down-converting of ultra-violet sunlight towards visual wavelengths that are better suited to solar electric energy.
  • The Ohio University group has carried out an experiment on a novel hybrid (amalgam) of Molybdenum with Tungsten, combined in an organic polymer plastic that is acting as a transparent semi-conductor. The experiment showed that more Sunlight is utilized due to the improved sensitivity of the material to the broad range of wavelengths of Sunlight and that high electron orbit states ("triplet states") were achieved thus enabling better opportunity for charge separation. The Ohio University group is a Center of Excellence for phosolar research.
  • Scientists at Leuven in Belgium have demonstrated a 40% increase in photocurrent from an experimental photo-cell. To a fluorescent donor layer they added a phosphorescent dopant made from "platinum octaethylporphyrin".4 Porphyrins are a group of naturally occurring pigmented photosensitisers, containing a metal atom in the core of the molecule, that play an important part in various biological processes. They can be excited by selective wavelengths of light to initiate photodynamic activity. In this case the metal atom is the phosphorescent metal platinum. This is a case of using the phosphorescent molecule in a secondary role rather than as a primary one: the sunlight excites both donor layer and the platinum layer; the latter layer becomes a secondary light source re-exciting the donor layer.
1. The term Phosolar was created in consistency with developments that had already taken place in the field of Light Emitting Diodes (LED). After LEDs were invented they were swiftly followed by Organic LEDs (OLED) and then by Phosphorescent OLEDs (PHOLED).
2. This description of phosphescent solar energy is couched in terms derived from conventional or classical physics. It could, however, be described in terms of Quantum Mechanics.
3. See also the news report:
4. Organic Electronics Volume 10, Issue 5, August 2009, Pages 1015-1019
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