1
Perovskite/c-Si tandem solar cells: 4-terminal and monolithic integration Synergy RTD 2013 Jérémie Werner, 1# Arnaud Walter, 2 Soo-Jin Moon, 2 Johannes Peter Seif, 1 Sylvain Nicolay, 2 Stefaan de Wolf, 1 Bjoern Niesen, 1,2 Christophe Ballif 1,2 1) Photovoltaics and Thin-Film Electronics Laboratory, EPFL, Rue de la Maladière 71, 2000 Neuchâtel, Switzerland 2) PV Center, Centre Suisse d’Electronique et de Microtechnique, Jacquet Droz 1, 2000 Neuchâtel, Switzerland # Correspondance: [email protected] Parasitic absorptions Reducing the parasitic absorption in the perovskite top cell is the key for high performance in both 4-terminal and monolithic tandem. In the case of 4-terminal tandem, the standard front electrode used in perovskite cell (FTO) need to be replaced by a TCO with lower free carrier absorption, e.g. ITO. Replacing FTO by ITO produces a current increase in the bottom cell of 3-4 mA/cm 2 . The photovoltaics market is dominated by wafer-based crystalline silicon solar cells. With a record efficiency of 25.6%, close to their theoretical maximum efficiency of 29.4%. Perovskite-based solar cells have recently made tremendous progress and currently reach efficiencies of up to 22.1% Perovskite/crystalline Si cells optimally use the solar spectrum: The perovskite cell absorbs the visible light, the crystalline Si cell the near-infrared light Numerical simulations have predicted perovskite/ crystalline Si tandem efficiencies of > 30% The perovskite top cell needs to be semitransparent and have high transmittance in the near-infrared → Need to replace opaque metal contact with transparent electrode Two tandem device architectures: four-terminal mechanically stacked or two-terminal monolithic tandem Sputtered transparent conductive oxide rear electrodes with metal oxide buffer layers enable semitransparent cells showing comparable performance as opaque references Using more transparent TCOs and substrates, as well as minimizing the reflection at the air interfaces allows to further enhance tandem performance The elimination of parasitic absorption (e.g. in FTO, spiro-OMeTAD) is crucial to reach higher tandem cell efficiencies World record performances on both 4-terminal and monolithic tandems: 4-terminal tandem measurements with efficiency of up to 25%, after mpp tracking of 500s Monolithic tandem cells with up to 21.2 and 19.2% efficiency, respectively on 0.17 and 1.22cm 2 aperture area. J. Werner et al., SolMat, 141 (2015) 407-413 Requirement: high near-infrared transparency for maximal light transmission to bottom cell J. Werner et al., SolMat, 141 (2015) 407-413 Sputtered amorphous TCO: IZO, high conductivity, high transparency, high mobility with low carrier density, reproducible and industrially compatible process, low-temperature deposition, no post-deposition treatment needed Rear electrode: sputter damage avoided with introduction of thin molybdenum oxide layer, no FF and V oc losses, J sc reduction due to lack of rear reflector Semitransparent cell performance comparable to opaque cells In the case of monolithic tandem, the highly doped hole transport layer, Spiro-OMeTAD, parasitically absorbs over the entire spectral range, and particularly for wavelengths below 400nm. → Jsc loss of about 2-3 mA/cm 2 when illuminate from spiro side. Reducing the thickness of spiro can help to recover some current <400nm. But changes interference pattern. Transparent Rear Electrode for Perovskite Solar Cells Introduction & Motivation Perovskite/c-Si monolithic tandem device Conclusions Perovskite/c-Si 4-terminal tandem device The perovskite cell is processed directly on top of the silicon bottom cell, connected by an intermediate recombination layer. low-temperature (<200°C) processed perovskite top cell on silicon heterojunction bottom cell Interferences play a large role on current matching Monolithic tandem efficiency (state-of-the-art): 21.2% on 0.17cm 2 and 19.2% on 1.22cm 2 , after >5min maximum power point tracking. 400 500 600 700 800 900 1000 1100 0.0 0.2 0.4 0.6 0.8 1.0 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 -40 -30 -20 -10 0 0 100 200 300 160 180 200 0.0 0.5 1.0 1.5 -15 -10 -5 0 0 100 200 300 400 500 160 180 200 220 EQE (-) Wavelength (nm) Aperture area: 1.22 cm 2 Top cell: 15.1/16.8 mA/cm 2 Bottom cell: 14.6/17.4 mA/cm 2 Total Reflectance a) c) Tandem: w/o ARF with ARF Single-junction: DSP-SHJ Perovskite Current density (mA/cm 2 ) Voltage (V) b) Tandem aperture area: 1.22 cm 2 Pmpp (W/m 2 ) Time (s) 192.5 w/o ARF with ARF Current density (mA/cm 2 ) Voltage (V) Aperture area: 0.17 cm 2 Pmpp (W/m 2 ) Time (s) 212 J. Werner et al., JPCL 2016, 7, 161-166 The perovskite cell is mechanically stacked on a crystalline Si cell, allowing for independent processing of both sub-cells. No constraints for the orientation/polarity of the perovskite cell. 3 highly transparent electrodes with low sheet resistance are required. The photocurrent in the silicon bottom cell is limited by parasitic absorption in the perovskite top cell J. Werner et al., Presented at MRS Spring 2016, Phoenix 4-terminal measurements: Semitransparent perovskite top cell (0.25 cm 2 ): 16% mpp tracker Silicon bottom cell, non-filtered, (4 cm 2 ): 21.7% Silicon bottom cell, filtered: 9% Total tandem: 25%mpp tracker
![[Enter your title here] - CreativeCreation - ronn andriessen.pdfTriple cation perovskite for tandem with c-Si cells Absolute efficiency increase of 2.4% compared to standalone c-Si](https://static.documents.pub/doc/80x56/60a80cae323c8f08c34d393b/enter-your-title-here-ronn-andriessenpdf-triple-cation-perovskite-for-tandem.jpg)
