New four-terminal tandem organic solar cell achieves 16.94% power conversion efficiency

Researchers at ICFO have fabricated a brand new four-terminal natural photo voltaic cell with a tandem configuration with a 16.94% energy conversion effectivity (PCE). The brand new machine consists by a extremely clear entrance cell that includes a clear ultrathin silver (Ag) electrode of solely 7nm, which ensures its environment friendly operation.

Two-terminal tandem organic solar cells (OSCs) symbolize probably the most promising approaches to deal with the transmission and thermalization losses in single-junction photo voltaic cells. These natural photo voltaic cells encompass entrance and rear subcells with various bandgaps, enabling broader absorption and use of the photo voltaic spectrum.

Nevertheless, reaching optimum efficiency in such configurations calls for a enough present stability between the 2 subcells. Furthermore, fabricating tandem natural photo voltaic cells of those varieties is difficult as a result of they want a sturdy interconnection layer able to facilitating environment friendly cost recombination whereas sustaining excessive transparency.

The four-terminal tandem configuration has emerged as a extremely environment friendly various technique in solar cell design. In contrast to the two-terminal strategy, this configuration options separate electrical connections for the clear entrance cell and the opaque again cell.

Consequently, the difficulty {of electrical} present matching is now not a limiting issue. This setup permits better flexibility in choosing the bandgaps of every cell of the tandem, thereby optimizing photon absorption and enhancing the general effectivity of photo voltaic power manufacturing.

Now, in a brand new research published within the journal Photo voltaic RRLICFO researchers Francisco Bernal-Texca, and Prof. Jordi Martorell describe the fabrication of a four-terminal tandem natural photo voltaic cell that has achieved a 16.94% energy conversion effectivity (PCE). Central to this achievement is the fabrication of an ultrathin clear silver electrode, a crucial part that performed a pivotal position in optimizing the efficiency of the tandem photo voltaic cell.

To manufacture the brand new machine, the researchers first explored the natural supplies destined for the photoactive layer of each cells. They examined the effectiveness of three distinct blends for the entrance cell, which is designed to reap the high-energy photons. The mix that carried out the most effective, named PM6:L8-BO, was lastly chosen. For the again opaque cell, the researchers determined to make use of the PTB7-Th:O6T-4F mix, with a slim bandgap, which makes it higher suited to soak up the infrared a part of the spectrum (low-energy photons).

After selecting the blends, the researchers used a numerical strategy to design the four-tandem OSC’s ultimate construction. They used the matrix formalism mixed with the standard inverse problem-solving methodology to seek out the optimum efficiency and the ultimate configuration of the photo voltaic machine.

The fabrication of an ultra-thin clear silver electrode with a thickness of solely 7nm was the important thing ingredient within the present analysis. This factor was positioned behind the entrance cell, making certain a great mild transmission to energy the again cell. Typical high Ag electrodes utilized for clear photo voltaic cell purposes sometimes vary in thickness from 9 to fifteen nm.

Its manufacturing demanded meticulous management of laboratory situations to make sure precision and consistency. The electrode was then stacked with three dielectric layers alternating tungsten trioxide (WO3) and lithium fluoride (LiF). This photonic multilayer construction has a vital position, as a result of it’s positioned between the 2 cells to facilitate environment friendly and uniform mild distribution.

“This structure exhibits a high transmission in the 750–1,000 nm range and a high reflectivity in the 500–700 nm range,” researchers wrote.

“The development of a transparent silver intermediate electrode is crucial for the efficient operation of the solar cell. It must present a delicate balance, being transparent enough to allow light to reach the back cell while maintaining high electrical conductivity to ensure the optimal performance of the front cell,” mentioned Bernal, ICFO researcher and first writer of the research. “Being able to fabricate an electrode of only 7nm without observing losses in the front transparent cells is a significant advancement in the field of transparent cells.”

The researchers examined the photovoltaic efficiency of the machine beneath 1 solar of illumination with a photo voltaic simulator and measured its quantum effectivity. The machine achieved a 16.94% of power conversion efficiencywhich to this point could be the best reached for a four-terminal tandem natural cell. The authors of the research comment that the present official report in effectivity for natural tandem units is 14.2% and that the final reported PCE for 4-terminal natural tandems is 6.5%.

“Our research holds potential applications in photoelectochemical cells (PEC), addressing crucial electrical requirements such as providing the necessary voltage to surpass established for driving water splitting or CO₂ reduction reactions like in SOREC2 project,” defined Prof. Martorell, researcher at ICFO and SOREC2 venture coordinator.

“The methodology for the design and implementation of the four-terminal tandem structure could be applied to design news systems where an adequate distribution of light in the elements is crucial for the performance of a certain device.”

The researchers are at present directing their focus in the direction of refining, tuning and enhancing the methodology and structural design tailor-made for purposes equivalent to photo voltaic fuels, the place tandem units maintain widespread applicability. By optimizing the methodology and design methods, researchers goal to unlock the total potential of those units in harnessing photo voltaic power for various and sustainable power conversion processes, equivalent to CO₂ conversion and valorization.