Semiconducting Nanomaterials for OLEDs and OPVs
Organic light-emitting diodes (OLEDs) and organic photovoltaics (OPVs) are two of the leading optoelectronic technologies currently available at industrial scales. At the heart of these components is a functional thin film of metal oxide or semiconducting nanomaterials, which facilitate the transport of electrons and positively-charged electron holes from one diode to another. These structures are lithographically deposited onto a substrate or a metallic cathode that either introduces an electrical current into the thin film; or converts harvested photons into a voltage. Reaching new standards for high-performance display and ultra-efficient solar conversion technologies; OLEDs and OPVs are the frontrunning achievements of modern electronic printing techniques.
Semiconducting Nanomaterials Outlined
The behaviour of semiconductors changes dramatically when reduced to a scale of 20 nanometres (nm) or below. Like macroscale semiconductors, semiconducting nanomaterials can carry a current via a flow of either electrons or positively-charged electron holes, albeit with significantly improved efficiency. Reducing the functional material to nanoscale dimensions maximises the number of atoms situated at heterojunctions and surface interfaces, accelerating charge transferral through the device.
Silicon is one of the most pervasive semiconductor materials used to construct OPVs. Single-junction solar cells are comprised of layers of doped p-type and n-type silicon semiconductors sandwiched between an anode and a cathode. This junction is tuned to a specific bandgap, resulting in low out of band attenuation and a theoretical maximum efficiency of roughly 33%. Multi-junction, or tandem, solar cells comprise multiple semiconductor materials for additional p-n junctions to increase the range of wavelength absorbance and significantly improve solar cell efficiency. This is largely attributed to the improved interfacial behaviour of tandem junctions utilising multiple semiconducting materials.
Novel OPVs typically comprise a multilayer system with an electron- or electron-hole blocking layer deposited on a conductive substrate with sequential layers of an electron acceptor, an additional block layer, and finally an electrode. This enables photons to be readily absorbed and converted into excitons via the photoelectric effect. OLEDs operate on the inverse principle; turning excited electrons into photons and emitting them through a transparent substrate.
Semiconducting Nanomaterials from Avantama
Avantama specialises in the development and production of semiconducting nanomaterials that can match the impressive rate of modern research and development into new printed electronics arrays. We have developed a range of inorganic semiconducting nanomaterials suitable for solution processing of OLED and OPV devices. These include tungsten, molybdenum, zinc, and aluminium-doped zinc oxides (WOx, MoOx, ZnO, and Al:ZnO). If you would like more information about the functionalities and applications of these novel semiconducting materials, explore our previous blog posts:
- MoO3: The Applications of Molybdenum Trioxide Nanoparticles;
- The Properties and Applications of ZnO Nanoparticles