Enel Green Power and CEA achieve 24.9% cell efficiency on 9cm²

[Tandem Perovskite-Silicium]

Research and innovation

Published on 04/14/2022

Tandem Perovskite-Silicium

The discovery of the photovoltaic properties of halogenated organometallic perovskite (PK) materials offers the possibility of a remarkable technological leap for solar cells. Indeed, such materials open the way to conversion efficiencies above 30% by combining them with a lower band-gap material such as silicon (Si). They also have the advantage of being able to be implemented by liquid process, which allows for low-cost industrialization and is compatible with high throughputs.

The CEA-Liten at INES, in collaboration with ENEL Green Power, is developing the two-terminal Si/PK tandem technology with the aim of achieving high efficiencies in conventional photovoltaic formats with processes that allow their industrialization. Two approaches are being studied in parallel in the CEA laboratories: a NIP-type architecture with a record efficiency of 23.7% on active area, and since 2021 a PIN-type architecture.

The last few months have been busy working on the PIN architecture with:

The development of the initial 9 cm² architecture
The adaptation of the heterojunction silicon cell, realized on the CEA’s pilot line, and recombination layer for integration in tandem
A P-layer allowing depositing perovskite without preliminary treatment and the optimization of the N-type transport layers
The introduction of a large gap perovskite
The adding of an anti-reflection layer that allows a gain in current and participates in the balancing of the currents

The result is there: a new record was reached with a cell showing an efficiency of 24.9% on a surface of 9cm² and a, Voc >1800 mV, with shading correction.

This result is to be compared with the results obtained by other research groups in the world, with different approaches, considering the conversion efficiency and the surface of the device. At the time of publication, the record is currently held by HZB with 29.8% for a 1cm² device, with shading correction (https://www.pv-magazine.com/2021/11/22/helmholtz-center-achieves-29-80-efficiency-for-perovskite-silicon-tandem-solar-cell/).

Further optimization is needed to improve the performance of the Si/PK tandem cells on 9 cm² before moving to larger areas.

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