Higher Efficiencies with little extra costs#

Perovskite Silicon Tandem Solar Cells promise efficiency of over 30%.

Perovskite Silicon Tandem Photovoltaics

Perovskite silicon tandem solar cells promise to reduce electricity generation costs and lower resource consumption compared to conventional silicon solar cells. The perovskite solar cell is deposited directly onto the silicon solar cell in a tandem stack. Since the perovskite semiconductor has a higher energy band gap than silicon, the perovskite solar cell can utilize high-energy photons better than the silicon solar cell. In turn, the silicon solar cell can efficiently use the low-energy photons, which are transmitted through the perovskite solar cell. The overall efficiency increases and efficiencies of over 30% are possible.


  • 25.1% efficiency for perovskite silicon tandem solar cell with stable perovskite absorber with high band gap. Efficiency is rapidly increasing.
  • Detailed cost calculations show potential cost advantage for perovskite silicon tandem solar cells in the future
  • Fraunhofer lead project "MaNiTU"for the development of lead-free perovskite silicon tandem solar cells

Research & Development#

© Fraunhofer ISE

As part of the PersiST project funded by the German Federal Ministry for Economic Affairs and Energy (BMWi), Fraunhofer ISE was able to achieve over 25 % efficiency for a perovskite silicon tandem solar cell.

An a-Si/c-Si heterojunction solar cell textured on the back surface was used for the bottom cell. A layer of indium-doped tin oxide (ITO) served as the electrical connection to the perovskite solar cell. On top of this, we deposited a very thin layer of an organic hole conductor, followed by the perovskite absorber. Using the absorber compound FA0.75Cs0.25Pb(I0.8Br0.2)3, we were able to achieve an optimal band gap of 1.68 eV and high stability. A layer of evaporated C60 acted as electron contact, followed by SnOx and another ITO layer.

In the Fraunhofer lighthouse project MaNiTU, we are developing this technology further with the aim of achieving even higher efficiencies. We are also researching lead-free alternatives for the absorber. Based on the assumption that we succeed in achieving high efficiencies of 28 % and a service life of at least 23 years for the tandem cells, an initial life cycle analysis indicates that great added ecological value exists already at this point. This is due to the fact that the layers of the perovskite solar cell are very thin and that the higher efficiency significantly reduces the CO2 footprint per kilowatt hour of electricity generated.

Working at the glove box on an evaporation mask for metal contacts on perovskite solar cells
© Fraunhofer ISE/Foto: Dirk Mahler
Working at the glove box on an evaporation mask for metal contacts on perovskite solar cells.

The situation is similar for the electricity generation costs: The production of the additional layers for the perovskite solar cell is prospectively possible at very low costs. Overall, the efficiency increases significantly and the cost per kWh of electricity generation decreases. In a detailed cost analysis, we found that perovskite silicon tandem solar cells are particularly promising for rooftop and other applications with area constraints. Aside from this, they promise a significant cost advantage over single-junction silicon solar cells, assuming that perovskite technology stays on track and reaches a level where the efficiency of industrial-scale tandem solar cells exceeds 30% in the near future. The aim is to implement cost-effective processes and make the lifetime of the modules comparable to that of silicon.

Further Information on this Research Topic:#

R&D Infrastructure

Center for High Efficiency Solar Cells

Research Project


Fraunhofer Lighthouse Project


Current publications - Perovskite Silicon Tandem Photovoltaics#

YearTitle/AuthorDocument Type
202025.1% High‐Efficiency Monolithic Perovskite Silicon Tandem Solar Cell with a High Bandgap Perovskite Absorber
Schulze, P.S.C.; Bett, A.J.; Bivour, M.; Caprioglio, P.; Gerspacher, F.M.; Kabakli, Ö.S.; Richter, A.; Stolterfoht, M.; Zhang, Q.; Neher, D.; Hermle, M.; Hillebrecht, H.; Glunz, S.W.; Goldschmidt, J.C.
Journal Article
2020High Bandgap Absorber for Monolithic Perovskite Silicon Tandem Solar Cells Reaching 25.1% Certified Efficiency and Ways Beyond
Schulze, P.S.; Bett, A.J.; Kabakli, Ö.S.; Winkler, K.M.; Mundt, L.E.; Gerspacher, F.M.; Zhang, Q.; Hofmann, C.L.; Bivour, M.; Hermle, M.; Glunz, S.W.; Hillebrecht, H.; Goldschmidt, J.C.
Conference Paper
2020Passivating contacts and tandem concepts: Approaches for the highest silicon-based solar cell efficiencies
Hermle, M.; Feldmann, F.; Bivour, M.; Goldschmidt, J.C.; Glunz, S.W.
Journal Article
2020Perovskite Hybrid Evaporation/ Spin Coating Method: From Band Gap Tuning to Thin Film Deposition on Textures
Schulze, P.S.C.; Wienands, K.; Bett, A.J.; Rafizadeh, S.; Mundt, L.E.; Cojocaru, L.; Hermle, M.; Glunz, S.W.; Hillebrecht, H.; Goldschmidt, J.C.
Journal Article
2020The Race for the Best Silicon Bottom Cell. Efficiency and Cost Evaluation of Perovskite-Silicon Tandem Solar Cells: Presentation held at 37th European Photovoltaic Solar Energy Conference and Exhibition, EU PVSEC 2020, Lisbon, Portugal, 7th September 2020, online
Messmer, C.; Goraya, B.S.; Nold, S.; Schulze, P.S.; Schön, J.; Goldschmidt, J.C.; Bivour, M.; Glunz, S.W.; Hermle, M.
2020Tandem cells under the weather
Goldschmidt, J.C.
Journal Article
2020Two-Terminal Perovskite Silicon Tandem Solar Cells with a High-Bandgap Perovskite Absorber Enabling Voltages over 1.8 V
Bett, A.J.; Schulze, P.S.C.; Winkler, K.; Kabakli, Ö.; Ketterer, I.; Mundt, L.; Reichmuth, S.K.; Siefer, G.; Cojocaru, L.; Tutsch, L.; Bivour, M.; Hermle, M.; Glunz, S.W.; Goldschmidt, J.C.
Journal Article
2020Vapor-Phase Formation of a Hole-Transporting Thiophene Polymer Layer for Evaporated Perovskite Solar Cells
Suwa, K.; Cojocaru, L.; Wienands, K.; Hofmann, C.; Schulze, P.S.C.; Bett, A.J.; Winkler, K.; Goldschmidt, J.C.; Glunz, S.W.; Nishide, H.
Journal Article
2019Efficiency Enhancement and Hysteresis Mitigation by Manipulation of Grain Growth Conditions in Hybrid Evaporated-Spin-Coated Perovskite Solar Cells
Rafizadeh, S.; Wienands, K.; Schulze, P.S.; Bett, A.J.; Andreani, L.C.; Hermle, M.; Glunz, S.W.; Goldschmidt, J.C.
Journal Article
2019The Role of Surface Passivation Layer Preparation on Crystallization and Optoelectronic Performance of Hybrid Evaporated-Spincoated Perovskite Solar Cells
Rafizadeh, S.; Wienands, K.; Mundt, L.E.; Bett, A.J.; Schulze, P.S.C.; Andreani, L.C.; Hermle, M.; Glunz, S.W.; Goldschmidt, J.C.
Journal Article
This publication list has been generated from the publication database Fraunhofer-Publica.