STMicroelectronics released details of an advanced research programme that it hopes will substantially reduce the cost of generating electricity from solar power. The research team, based in Catania and Naples, Italy, is focusing on applying expertise in nanotechnology to the development of new solar cell technologies. It is hoped the final products will eventually be able to compete commercially with conventional electricity generation methods such as burning fossil fuels or nuclear reactors.

STMicroelectronics released details of an advanced research programme that it hopes will substantially reduce the cost of generating electricity from solar power. The research team, based in Catania and Naples, Italy, is focusing on applying expertise in nanotechnology to the development of new solar cell technologies. It is hoped the final products will eventually be able to compete commercially with conventional electricity generation methods such as burning fossil fuels or nuclear reactors.

Existing solar cell technologies are mainly based on semiconductor materials such as silicon and involve high material costs. Although the "fuel" for a solar-powered generator is free sunlight, the overall cost of solar-generated electricity amortised over the lifetime of the solar cell of typically 20 years is around ten times higher than the cost of electricity generated by burning fossil fuels.

Semiconductor-based solar cells have the highest efficiency (defined as the electrical energy produced for a given input of solar energy) but there is little that can be done to either increase the efficiency or reduce the manufacturing cost. ST is therefore pursuing alternative approaches in which the aim is to produce solar cells that may have lower efficiencies (for example, 10% instead of 15-20%) but are much cheaper to manufacture.

The ST team is following two approaches. One - the Dye-Sensitized Solar Cell (DSSC) invented in 1990 by Professor Michael Graetzel of the Swiss Federal Institute of Technology - uses a similar principle to photosynthesis. DSSCs mimic the mechanism that plants use to convert sunlight into energy. Each function is performed by a different substance - an organic dye (photosensitiser) absorbs the light and creates electron-hole pairs, a nanoporous (high surface area) metal oxide layer transports the electrons and typically a liquid electrolyte transports the holes.

"One of the most exciting avenues we are exploring is the replacement of the liquid electrolytes that are mostly used today for the hole-transport function by conductive polymers," says Dr Salvo Coffa, head of ST's solar cell group. "This could lead to further reductions in cost per Watt, which is the key to making solar energy commercially viable."

The ST team is also developing low cost solar cells using a full organic approach, in which a mixture of electron-acceptor and electron-donor organic materials is sandwiched between two electrodes. The nanostructure of this blend is crucial for the cell performance because the electron-donor and electron-acceptor materials have to be in intimate contact at distances of less than 10nm. ST plans to use Fullerene (C60) as the electron-acceptor material and an organic copper compound as the electron-donor.

In a conventional solar cell, a single material such as silicon performs all three of the essential functions - conversion of photons into charge carriers, their separation and conduction to the collecting contacts of the cell creating the voltage. To perform these three tasks simultaneously with high efficiency, the semiconductor material must be of very high purity - the main reason why silicon-based solar cells are too costly to compete with conventional means of producing electric power.

AngelTech Live III: Join us on 12 April 2021!

AngelTech Live III will be broadcast on 12 April 2021, 10am BST, rebroadcast on 14 April (10am CTT) and 16 April (10am PST) and will feature online versions of the market-leading physical events: CS International and PIC International PLUS a brand new Silicon Semiconductor International Track!

Thanks to the great diversity of the semiconductor industry, we are always chasing new markets and developing a range of exciting technologies.

2021 is no different. Over the last few months interest in deep-UV LEDs has rocketed, due to its capability to disinfect and sanitise areas and combat Covid-19. We shall consider a roadmap for this device, along with technologies for boosting its output.

We shall also look at microLEDs, a display with many wonderful attributes, identifying processes for handling the mass transfer of tiny emitters that hold the key to commercialisation of this technology.

We shall also discuss electrification of transportation, underpinned by wide bandgap power electronics and supported by blue lasers that are ideal for processing copper.

Additional areas we will cover include the development of GaN ICs, to improve the reach of power electronics; the great strides that have been made with gallium oxide; and a look at new materials, such as cubic GaN and AlScN.

Having attracted 1500 delegates over the last 2 online summits, the 3rd event promises to be even bigger and better – with 3 interactive sessions over 1 day and will once again prove to be a key event across the semiconductor and photonic integrated circuits calendar.

So make sure you sign up today and discover the latest cutting edge developments across the compound semiconductor and integrated photonics value chain.

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