Asolaristor (fromSOLAR celltransISTOR) is a compact two-terminal self-poweredphototransistor. The two-in-one transistor plus solar cell achieves the high-low current modulation by amemresistive effect in the flow of photogenerated carriers. The term was coined by Dr Amador Perez-Tomas working in collaboration with otherICN2 researchers in 2018 when they demonstrated the concept in aferroelectric-oxide/organic bulk heterojunction solar cell.[1]
In a basic solaristor embodiment, the self-powered transistor effect is achieved by the integration of a light absorber layer (a material that absorbsphoton energy) in series with a functionalsemiconductor transport layer, which internal conductivity or contact resistance can be modified externally.
In general, the light absorber is a semiconductorp–n junction that:
Additionally, inthin-film solar cells, buffer electron and hole semiconductor transport layers are introduced at the respective metal electrodes to avoid electron-hole recombination and to remove the metal/absorberSchottky barrier.
A solaristor effect is achieved by modifying the internal field properties or the overall conductivity of the solar cell.
Ferroelectric solaristors. One possibility is the use offerroelectric semiconductors as transport layers. A ferroelectric layer can be seen as a semiconductor with switchable surface charge polarity. Because of this tuneable dipole effect, ferroelectrics bend theirelectronic band structure and offsets with respect to adjacent metals and/or semiconductors when switching the ferroelectric polarization so that the overall conductivity can be tuned orders of magnitude.
Conventionalphotodiodes orphotodetectors do not switch as aphototransistor does when biased through its third terminal (gate). An additional advantage of a solaristor is, therefore, the potential reduction of the standard phototransistor's area and interconnection complexity. By using solaristors, it would be possible in theory to replace the in-plane three-electrode architecture by a vertical, two-electrode photodiode-like architecture in systems like photo-sensors, cameras, or displays.
