by Riko Seibo
Tokyo, Japan (SPX) Feb 08, 2026
A analysis workforce from the Wuhan Nationwide Laboratory for Optoelectronics and the College of Optical and Digital Info at Huazhong College of Science and Expertise has reported a brand new advance in all perovskite tandem photo voltaic cells, resolving a key bottleneck in tunnel junction design.
All perovskite tandem photo voltaic cells are considered a excessive potential photovoltaic expertise, with theoretical energy conversion efficiencies approaching about 45 p.c. In observe, nonetheless, system efficiency has lagged behind these limits, partly due to losses and resistance on the tunnel junction that connects the extensive bandgap prime cell to the low bandgap backside cell.
Within the work reported by the workforce, the tunnel junction is fashioned by a SnO2/metallic/PEDOT:PSS stack that hyperlinks the electron transport layer of 1 sub cell to the outlet transport layer of the opposite. Utilizing quantitative Silvaco TCAD simulations, the researchers examined the basic physics of electron and gap tunneling by way of this junction and the way these processes depend upon materials parameters and metallic work perform.
The simulations present that the intrinsic properties of the cost transport layers create an inherent imbalance in tunneling. In SnO2, electrons have an efficient mass of roughly 0.2 occasions the free electron mass, whereas holes in PEDOT:PSS have an efficient mass of about 4.8 occasions the free electron mass. This huge disparity makes the outlet tunneling likelihood about 4 orders of magnitude decrease than the electron tunneling likelihood, turning gap transport into the dominant bottleneck within the junction.
To deal with this, the workforce targeted on how the work perform of the interlayer metallic controls the vitality limitations at each semiconductor interfaces. By scanning the metallic work perform from 4.2 electron volts to five.6 electron volts, they recognized an optimum worth close to 5.1 electron volts, consultant of noble metals corresponding to gold, that balances the interface limitations for electrons and holes.
At this optimum work perform, the vitality barrier for holes on the gap transport layer metallic interface is diminished to about 0.2 electron volts, whereas a reasonable barrier of round 0.5 electron volts stays for electrons on the electron transport layer metallic interface. This configuration allows environment friendly bidirectional tunneling reasonably than favoring one provider kind, which in flip lowers the equal collection resistance of the tunnel junction to the order of 10^-2 ohm sq. centimeters.
The authors describe this optimum configuration as a golden bridge inside the tandem structure, as a result of it permits costs generated in every sub cell to movement throughout the junction with minimal loss. Their outcomes spotlight that work perform pushed band alignment is the central design precept for engineering excessive efficiency tunnel junctions in all perovskite tandem photo voltaic cells.
Past figuring out a goal work perform, the examine supplies quantitative steerage on deciding on metals or metallic alloys to understand such junctions in observe. It additionally hyperlinks the microscopic tunneling conduct on the interfaces to macroscopic system stage figures of benefit, corresponding to collection resistance and total energy conversion effectivity, giving producers and system engineers a clearer path to strategy the theoretical efficiency limits of all perovskite tandem designs.
The publication features a schematic of the tandem system construction that emphasizes the position of the electron transport layer metallic gap transport layer tunnel junction, an equal circuit illustration of the 2 terminal tandem system, and a plot of simulated tunnel junction resistance as a perform of metallic work perform. Collectively, these outcomes map out how small adjustments in interlayer digital construction can produce massive features in operational effectivity.
The work is reported within the paper “Tunnel junction simulation of all-perovskite tandem photo voltaic cells,” printed within the journal Frontiers of Optoelectronics on January 7, 2026.
Analysis Report:Tunnel junction simulation of all-perovskite tandem solar cells
Associated Hyperlinks
Huazhong University of Science and Technology
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