Jinko Solar

The Australian National University (ANU) and partners Jinko Solar, the University of New South Wales (UNSW) and the University of Melbourne have reported progress towards cost‑effective silicon-perovskite tandem modules on passivating‑contact silicon cells, including monolithic tandem efficiencies up to 34.76% on Jinko’s TOPCon platform and 26.61% on 20 cm² devices processed with scalable blade‑coating. 

This work arises from the ARENA‑funded project “Cost‑effective Si/Perovskite Tandem Modules on Passivating Contact Si Cells” (TRAC005 / PRO‑1930), launched in December 2022 and scheduled to run until April 2028, which targets commercial‑ready monolithic silicon‑perovskite tandem (SPT) technology and significant production capacity by the end of the project.”

At a recent TaiyangNews conference, Menglei Xu, R&D Director at JinkoSolar, presented advancements in this field, including a perovskite-TOPCon tandem cell achieving a conversion efficiency of 34.76%. This milestone was enabled by the use of commercial TOPCon cells with efficiencies above 27% and open-circuit voltages (Voc) exceeding 748 mV, underscoring the importance of high Voc in two-terminal (2T) tandem configurations.

JinkoSolar’s approach involves depositing the perovskite layers on the rear side of the TOPCon cell, effectively flipping the structure to form the tandem device. Since the rear surface is initially planar, it must first be textured to form pyramidal features approximately 0.6-0.7 µm in size to enhance light management. Using a configuration with n-type poly-silicon fingers on the front and a full-area p-type poly layer on the rear, the team achieved an efficiency of 32.73%. However, parasitic absorption in the rear p-poly layer limited the short-circuit current density (Jsc) to 20.4 mA/cm², highlighting a key area for further optimization.

Researchers from the National University of Singapore, Zhejiang Jinko Solar, ShanghaiTech University, City University of Hong Kong, Photon etc. Ltd, Shanghai Jinko Green Energy Enterprise Management and National Yang Ming Chiao Tung University have proposed a molecular strategy to solve a key bottleneck in perovskite/TOPCon tandems: rapid perovskite crystallization and film degradation on thin, industrial silicon substrates with high thermal conductivity. 

By regulating the major organic cation FA⁺ using a dual‑mode‑coupled ligand, 2‑mercaptobenzothiazole (MBT), they achieve effective control over crystallization kinetics during perovskite deposition on tunnel oxide passivated contact (TOPCon) wafers.

Scientists at the Australian National University, along with collaborators from the University of Melbourne, the University of New South Wales, Zhejiang JinkoSolar, Zhejiang Key Laboratory of Advanced Tandem Photovoltaic Technology and Shanghai Jinko Green Energy Enterprise Management have mapped out how TOPCon silicon bottom cells can realistically compete with heterojunction (HJT) technology in perovskite/Si tandem solar cells.

HJT cells still deliver slightly higher open-circuit voltages and efficiencies, thanks to intrinsic amorphous silicon layers that give excellent surface passivation and low recombination. However, recent advances in TOPCon - including improved front-side passivation stacks, optimized n⁺ poly-Si contacts, and laser-assisted firing (LECO) - have pushed mass-produced TOPCon devices to Voc values around 740 mV and fill factors above 84%, shrinking the Voc gap with HJT to under 10 mV. Building on these developments, the team’s modelling shows that two-terminal (2T) perovskite/Si tandems with TOPCon bottom cells can realistically exceed 30% efficiency if parasitic absorption in poly-Si and passivation losses on textured surfaces are carefully controlled.

Jinko Solar recently announced a strategic cooperation agreement with XtalPi , a platform company that empowers R&D innovation with artificial intelligence and robotics. The two companies will jointly establish a joint venture to promote the collaborative R&D of high-throughput perovskite tandem solar cells based on AI technology.

Image credit: Jinko Solar

According to the agreement, the two parties will jointly build the world's first fully closed-loop perovskite-crystalline silicon tandem experimental line of "AI decision-making-robot execution-data feedback". Relying on Jinko Solar's photovoltaic R&D knowledge and XtalPi's unique advantages in fields like quantum physics algorithms, AI prediction models and large-scale robotic automated experiments, the focus will be on creating high-efficiency and high-stability perovskite tandem solar cells.