Risen Energy Hits 31.95% Efficiency in HJT-Perovskite Tandems

• Risen Energy hits 31.95% certified efficiency for its HJT-silicon/perovskite tandem on 1 cm²—1.988V open-circuit. Uniform perovskite layers via water-bath SAM boost transport and cut defects.

Risen Energy says its heterojunction (HJT) silicon–based perovskite tandem solar cell has reached 31.95% efficiency on a 1 cm2 device. The company reports the result was certified by authoritative institutions, with an open-circuit voltage of 1.988V.

Risen attributes the advance to its experience in both HJT and perovskite pathways and to manufacturing know-how developed from early HJT industrialization. It also points to a water-bath immersion process and related techniques to form a uniform perovskite layer on textured, pyramidal surfaces via a self-assembled monolayer (SAM), aiming to improve charge transport and lower defect density while leveraging the HJT bottom cell’s performance.

How did Risen achieve 31.95% certified HJT–perovskite tandem efficiency and 1.988V VOC?

• Integrated an HJT silicon bottom cell with a perovskite top cell designed for better spectral utilization and current matching, enabling the tandem to operate closer to its optimum operating point.
• Used high-quality HJT fabrication know-how—drawing on years of high-throughput, industrial HJT process development—to ensure low recombination in the silicon junction, supporting strong voltage delivery in the stack.
• Implemented interface and surface engineering to suppress non-radiative losses at the perovskite/silicon-related boundaries, helping preserve the tandem’s open-circuit voltage toward the 1.988V level.
• Applied a controlled water-bath immersion strategy for perovskite formation, tuned to promote uniform crystallization across the active area instead of relying on highly reactive, less controllable deposition steps.
• Employed a surface functionalization approach using a self-assembled monolayer (SAM) to improve nucleation and wettability on textured, pyramidal topographies, reducing voids, pinholes, and thickness nonuniformity.
• Leveraged the textured/pyramidal surface structure to enhance optical light trapping while maintaining electrical continuity, so improved absorption did not come at the cost of higher defect densities.
• Focused on defect reduction within the perovskite layer (via cleaner formation conditions and interface passivation), lowering trap-assisted recombination that would otherwise reduce both tandem efficiency and voltage.
• Optimized tandem stacking and recombination-management layers so that carrier extraction is efficient while recombination pathways between subcells remain minimal.
• Achieved high performance across a 1 cm² device area by pairing the above materials and interface controls with process uniformity compatible with scaled manufacturing.
• Submitted results for independent verification, enabling the 31.95% certified figure and confirming that the measured performance (including the 1.988V open-circuit voltage) met the requirements of the certifying bodies.