Hybrid Semiconductors Produce More Light with Less Power
By Mike Howie
Researchers at the Georgia Institute of Technology have found that a new type of hybrid semiconductor material could lead to lights, displays, lasers and solar panels that are not only more efficient but also easier to produce.
The material, called halide organic-inorganic perovskite, or HOIP, is assembled with non-covalent bonds and consists of an organic material sandwiched between two layers of inorganic crystal lattices. Individual units of the crystal take a form called perovskite, an even diamond shape with a metal center and halogens at the points. The result is a soft, flexible material that is easier to apply to surfaces than typical rigid semiconductors. In fact, the new material can even be painted on.
In addition to making the material easier to work with, the softness and flexibility also make it better suited to producing light from electricity.
Light is produced by applying energy to the electrons of an atom. When an electron absorbs energy, it makes a quantum leap into a higher orbit and releases the energy as light (or photons) when it returns to its original orbit. In established semiconductors, the electrons are trapped in specific areas that limit their range of motion. This makes it possible to excite electrons in unison, resulting in a more significant amount of light.
HOIPs, on the other hand, participate in the quantum action and facilitate movements that aren’t feasible in typical semiconductors.
Less Electricity, More Light
Thanks to their flexibility, HOIPs can support a few particles that typical semiconductors can’t. Electrons carry a negative charge, and when they jump from orbit, they leave an electron hole with a positive charge. The electron and hole can then circle around each other to form an imaginary or “quasi” particle called an exciton. The negative and positive attraction in an exciton is called binding energy, a high-energy phenomenon that’s great for emitting light.
With so much energy, excitons can escape their atoms and move around the material, where they can connect with other excitons to form biexcitons. They can even circle around atoms in the material lattice to form polarons. All this movement and interaction enhances the material’s light-emitting capabilities.
While it’s possible for conventional semiconductors to form excitons, they can only reliably do so at extremely cold temperatures. HOIPs, on the other hand, can reliably maintain excitons at room temperature.
HOIPs are also easier to produce than other semiconductors. Most traditional semiconductors are made under high temperatures and in small batches, but HOIPs can be made at low temperatures in large batches.
The Georgia Tech researchers predict that the material could be used to make LEDs, lasers and even window glass that could glow in a wide variety of colors. They also believe that lighting with HOIPs would require very little energy. Using the new material, it’s possible that solar panel manufacturers could produce higher-efficiency panels while reducing production costs.
A previous revolution in semiconductors gave us LEDs that have made so much of today’s technology possible. Similarly, HOIPs may be the technological evolution that lead us to a brighter future.
- Name other types of technology that could use HOIPs.
- In what ways could HOIPs improve everyday life?