Comprehensive defect passivation of Sn-Pb perovskites for application in tandem solar cells
Perovskite solar cells can be easily integrated into a multi-junction (tandem) architecture, thus can easily overcome the limitations of their single-junction counterparts. For this, they can be combined with silicon, CIGS or organic solar cells or with different perovskites. In all perovskite tandem solar cells (TSCs), top (narrow bandgap, NBG) and bottom (wide bandgap, WBG) subcells must be separately optimized to enhance open circuit voltage and fill factor. In this project, we use a comprehensive defect passivation approach to reduce recombination in both subcells and at their interconnection. Due to the limitations in measuring electro-optical properties of our NBG cells at our group, we seek a collaboration with another group which has capabilities to measure quantum efficiency and photoluminescence beyond 950 nm.
Status: Ongoing
Date of proposal: 28/02/2023
Start date: 23/06/2019
End Date: 23/06/2023
Used Instruments: EQE (External Quantum Efficiency) measurement setup. Photoluminescence (PL) measurement setup. JV (Current-Voltage) characterization equipment.
Experimental Technique: External Quantum Efficiency measurements. Photoluminescence spectroscopy. JV measurements.
Experiment Description: Characterization of top and bottom sub-cells in all perovskite tandem solar cells. Focus on understanding loss mechanisms in devices prepared in Konstanz. Inability to measure EQE beyond 950 nm due to limitations in Si detector. No existing setup for measuring PL spectrum of NBG perovskite (PL peak position 990-995 nm).
Type Samples: Perovskite films (both wide and narrow bandgaps). Half and full devices of tandem solar cells.
Sample Description: Multiple compositions of perovskite films. Single junction and multi-junction tandem solar cells.
Experiment Data Type: EQE measurements. Photoluminescence spectra. JV characteristics.
Characterization Technics: EQE characterization. Photoluminescence spectroscopy. JV characterization.
Characterization Data Type: EQE data for single junction and tandem solar cells. Photoluminescence spectra. JV curves (performance characteristics).
Analyzed Data: Analysis of performance limitations in tandem solar cells. Identification of high parasitic absorption in bottom cell (NBG perovskite). Assessment of impact of top perovskite absorber layer thickness.
Main Targets Project: To characterize the top and bottom sub-cell in perovskite tandem solar cells. To understand and address loss mechanisms in these devices. To overcome measurement limitations in EQE and PL for NBG perovskite.
Main Achievements Findings: Establishment of compatible setups and sample holders for long-term collaboration. Improvement in PCE from 19.5% to around 21% following modifications in device architecture. Design of new experiments leading to advancements in device performance.
Review 19
How would you describe your experience with the VIPERLAB opportunity? How did the visit at ENEA meet your expectations?
It was a wonderful experience. It certainly met my expectations and even beyond. Not only we were able to achieve the objective set out for this trip but also we discussed possibilities for long-term collaborative work.
Did you face any difficulties during your visit or application process?
Not at all. Everything was arranged so well, both in terms of logistics and scientific activities at the ENEA. Credit goes to Dr Francesco, Dr. Paola and Dr Lucia and their group members for organizing everything so well and for being so welcoming.
What other VIPERLAB activities have you participated in, or would you like to participate in?
I have participated in the workshop held in May (online participation) at ENEA. I would be happy to join workshops/lectures (online preferably) and if possible, carry out a follow-up visit to complete the measurements.
Does this VIPERLAB experience at ENEA bring you closer to your research objectives? How?
Yes, at Konstanz, we established all-perovskite baseline for the first time and we were not able to understand fully the limitations in the devices stack. The extensive measurements at ENEA, particularly, the EQE measurements helped us understand that the performance is mainly limited due to mismatch in the Jsc, which is governed by the bottom (narrow bandgap) cell.
Did you publish or present your collected results in a paper or conference?
Not yet, but I plan to present these results in upcoming EMRS (Fall, Warsaw). We also aim to include these results in a publication that will hopefully be submitted after Summer.