UNSW and UtmoLight set 23.5% efficiency record for large-area perovskite solar submodule

The work was led by Scientia Professor Xiaojing Hao at UNSW’s School of Photovoltaic and Renewable Energy Engineering, with Dr Zhen (Jan) Li and Dr Ziyue Feng.

UtmoLight, a China-based company, contributed expertise in large-area processing and module fabrication.

The submodule measures 30cm by 30cm, with an aperture area of 676cm². Small laboratory cells are typically around 1cm². The announcement did not name the previous record holder, the certifying laboratory or the measurement standard.

The team removed the nickel oxide layer commonly used in perovskite cells. UNSW said the layer can react with the perovskite, adding instability and an extra manufacturing step.

Instead, a hole-selective contact forms directly during fabrication, rather than through layer-by-layer deposition. The team achieved this through new materials and a different fabrication approach.

Hao said the aim goes beyond setting another efficiency record. Materials that perform well in a small laboratory device do not necessarily behave the same way in larger areas, so the team is designing materials and interfaces that stay effective under the conditions needed for large-area fabrication.

The team hopes to produce a full-scale module with a 2.8m² area in the coming months, with the target efficiency for that module being around 18% to 19%.

Hao, speaking to PV Tech Premium, previously set out a staged efficiency roadmap for kesterite’s commercialisation, telling PV Tech that reaching around 20% efficiency would represent a genuine opportunity for commercial uptake, with intermediate targets of 15% and 17% needed to build confidence in the technology along the way.

UtmoLight unveiled a 2.8m² module rated at 450W with 16.1% full-area efficiency in November 2024.

It later started what it called China’s first gigawatt-scale production line, with a full-capacity output of about 1.8 million modules a year, according to the company.

Funding and wider research continue in parallel

The Australian Renewable Energy Agency (ARENA) announced up to AU$105.6 million (US$70.5 million) for 20 solar research and development projects in late August. The agency describes it as its largest single solar PV research investment.

Hao received AU$6.3 million for a project to make perovskite-silicon tandem panels more efficient and reliable. UNSW also received AU$5.6 million to field test commercial perovskite and tandem modules for stability.

Hao’s team is also working on kesterite, a thin-film material made from copper, zinc, tin and sulphur. It claimed a 13.2% efficiency for a high-bandgap kesterite cell in January 2025. In August, it reported a certified 12.4% for copper zinc tin sulphide cells by preventing copper drift during manufacturing.

Hao has drawn a distinction between her team’s kesterite work and much of the perovskite field.

She has said that perovskite research has often pursued high efficiency first and addressed stability afterwards, whereas her group starts with an abundant, environmentally friendly, and stable material.

She expects silicon to remain the dominant PV technology, with perovskites and kesterite finding their clearest opportunity in tandem cells.

Separate UNSW research reported by PV Tech in April found that newer silicon cell designs such as TOPCon and heterojunction may degrade faster than expected under ultraviolet exposure.

UNSW’s Yansong Shen also told PV Tech in May that the industry could exhaust the world’s silver supply within five years unless module recycling is scaled up to a commercial level.

Despite the result, UNSW said further work is needed on efficiency, reproducibility and long-term stability before wide deployment.