Karlsruhe Institute of Technology researchers achieved 30.2% efficiency in perovskite-silicon tandem cells using a hybrid inkjet-printing process for perovskite absorber deposition
Dip-coating was used to deposit the SAM-based HTL on textured silicon and the interfacial passivation layer above the perovskite absorber
A 12.96 cm² single-junction perovskite mini-module achieved 17.8% efficiency
Researchers at Karlsruhe Institute of Technology (KIT), Germany, have demonstrated a scalable process route for perovskite-silicon tandem cells, achieving a maximum cell efficiency of 30.2%. The team used a two-step hybrid inkjet printing approach for the perovskite absorber layer and a dip-coating method for the hole transport layer (HTL) and interfacial passivation layers.
First, a self-assembled monolayer (SAM)-based HTL was deposited on a substrate (for perovskite-only cells) using 2PACz or on the silicon surface (for tandem cells) using Ph4PACz. This was achieved by dip-coating. The perovskite absorber was then formed through the hybrid two-step process, with inorganic precursors deposited by thermal evaporation, followed by inkjet printing of the organic precursors. Subsequently, a passivation layer was applied via dip-coating.
The optimized deposition processes were integrated with textured silicon heterojunction (HJT) bottom cells to fabricate monolithic perovskite-silicon tandem devices. The researchers used a wide-bandgap perovskite top cell and a textured silicon bottom cell. The champion tandem cell achieved a PCE of 30.2%, with an open-circuit voltage of 1.94 V, a short-circuit current density of 20.4 mA/cm², and a fill factor of 75.8%. The device maintained an efficiency above 30% during 10 minutes of maximum power point tracking. The researchers describe this as the first demonstration of a perovskite-silicon tandem cell exceeding 30% efficiency with an inkjet-printing-based perovskite absorber deposition process.
To evaluate the potential for larger-area deposition, the team fabricated a single-junction perovskite mini-module with an active area of 12.96 cm². The module consisted of nine series-connected cell stripes, each with an active area of 1.44 cm², formed using laser scribing. It achieved a PCE of 17.8%. When compared with the median efficiency of the smaller cells, the efficiency loss was 0.53 percentage points per decade of area scaling.
These results demonstrate the potential of inkjet printing and dip-coating or tandem cell fabrication. However, some challenges remain: the tandem devices recorded a fill factor of 75.8%, which the researchers attributed to a not-yet-optimized tandem architecture on a textured silicon surface. Further improvements in laser-scribing precision and process control will be important in translating the laboratory process into an industrial manufacturing route. Access the complete research publication here.
