Subscriber access provided by UNIV OF DURHAM
Energy Express
21.8% Efficient Monolithic Perovskite/HomoJunction-Silicon Tandem Solar Cell on 16 cm2 Jianghui Zheng, Hamid Mehrvarz, Fa-Jun Ma, Cho-Fai Jonathan Lau, Martin Green, Shujuan Huang, and Anita W. Y. Ho-Baillie ACS Energy Lett., Just Accepted Manuscript • DOI: 10.1021/acsenergylett.8b01382 • Publication Date (Web): 31 Aug 2018 Downloaded from http://pubs.acs.org on August 31, 2018
Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.
is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.
Page 1 of 8 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
ACS Energy Letters
21.8% Efficient Monolithic Perovskite/Homo-Junction-Silicon Tandem Solar Cell on 16 cm2 Jianghui Zheng*,†, Hamid Mehrvarz†, Fa-Jun Ma†, Cho Fai Jonathan Lau, Martin A. Green, Shujuan Huang and Anita W. Y. Ho-Baillie* Australian Centre for Advanced Photovoltaics, School of Photovoltaic and Renewable Energy Engineering, University of New South Wales (UNSW), Sydney 2052, Australia †
These authors contribute equally to this work * Corresponding Author: Email:
[email protected] (A. Ho-Baillie),
[email protected] (J. Zheng)
1
ACS Paragon Plus Environment
ACS Energy Letters 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Abstract Monolithic (FAPbI3)0.83(MAPbBr3)0.17 perovskite/rear-textured-homo-junction-silicon tandem solar cell with steady-state 21.8% efficiency has been achieved on 16 cm2 using a new front top metal grid design producing an impressive fill factor (76% under forward scan or 78% under reverse scan). The efficiency and fill factor are the highest for monolithic perovskite/Si tandem larger than 10 cm2.
TOC graphic
2
ACS Paragon Plus Environment
Page 2 of 8
Page 3 of 8 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
ACS Energy Letters
The rapid improvement of perovskite solar cells in terms of power conversion efficiency (PCE) makes it a promising material for further efficiency enhancement for silicon photovoltaic technology by using a tandem approach.1-3 Certified PCE of 27.3% (on 1 cm2 by Oxford PV) and 25.2% (on 1.419 cm2 by EPFL) have been recently announced or reported for monolithic perovskite/silicon tandem.4, 5 The latest recent has exceeded the record efficiency of single junction silicon solar cell at 26.7%.6 Table S1 in supporting
information
(SI)
summarized
results
of
monolithic
2-terminal
perovskite/silicon tandem device to date. Out of a total of 15 work, only 4 used the homo-junction Si cells as the bottom cells for the tandem while the rest used hetero-junction silicon (SHJ) solar cells as the bottom cells due to their high open-circuit voltage and PCE. However, homo-junction silicon cells currently dominate (around 90% of) the world market with a well-established industry process. Furthermore, large area tandem demonstration is also essential for it to be commercially relevant. To-date, there are only two monolithic perovskite/silicon tandem demonstrations on area > 10 cm2. The work reported by Sahli et al. employed a SHJ cell as the bottom cell and achieved a steady-state PCE of 18.0% on 13 cm2. 7 Our previous work employed a homo-junction cell as the bottom cell and achieved a steady-state PCE of 17.1% on 16 cm2 which is the largest area for monolithic perovskite/silicon tandem to-date. 8 None of these work employ indium tin oxide (ITO) as the interface layer for integrating the perovskite cell onto the Si cell. Nano-crystalline Si (nc-Si) was used
3
ACS Paragon Plus Environment
ACS Energy Letters 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
instead by Sahli et al.. In our work, no additional interface layer was used. Rather, a SnO2 layer doubles its function as the electron transport for the perovskite top cell and as the recombination layer between the top perovskite cell and silicon bottom cell. The lack of lateral conductivity in Sahli et al.’s nc-Si layer and in our SnO2 layer provides ease of large-area-scale-up due to the localization of undesirable shunts. However, both of these tandems have far-less-than-ideal fill factor of only 65% 7 and 68% 8. This work builds on the previous work with a few cell design changes. A new metal grid design is used for the large area demonstration on 16 cm2, a mixed perovskite absorber instead of MAPbI3 (MA = methylammonium) is used for the top cell and a rear textured instead of a planar homo-junction-silicon bottom cell is used in this work (see Abstract Graphic). Experiment details can be found in the SI. As shown in Figure 1a, the 16 cm2 achieves a PCE of 21.9% under reverse-scan with an open-circuit voltage (VOC) of 1.74 V, a short-circuit current density (JSC) of 16.2 mA/cm2 and a fill factor (FF) of 78% or a steady state efficiency of 21.8%. By replacing MAPbI3 with (FAPbI3)0.83(MAPbBr3)0.17 (FA = formamidinium) perovskite for the top cell, the VOC of tandem device has been enhanced and the hysteresis has been also significantly reduced. This is because the mixed perovskite has a higher band gap and better quality as anti-solvent method is used for its deposition (instead of a 2-step process used for the MAPbI3 in previous work 8). The ratio of PCEFWD/PCEREV in the previous work for the 16 cm2 tandem cell was 0.89 while the
4
ACS Paragon Plus Environment
Page 4 of 8
Page 5 of 8 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
ACS Energy Letters
ratio for the 16 cm2 tandem cell in this work is 0.97. By employing the rear textured bottom silicon cell, the JSC of the tandem device has been improved to 16.2 mA/cm2 (Figure 1b) as opposed to 15.6 mA/cm2 in previous work. Another significant improvement can be seen in the FF with a high value of 78% (which is a 10% absolute improvement from that reported in our last work) as a result of new metal grid design for the top electrode. This results in a much lower voltage drop due to series resistance across the cell compared to previous design. Figure 1c shows the maximum voltage drop in the new metal grid design is 35 mV while the voltage drop in the old design as shown in Figure 1d is as high as 100 mV assuming metal contact is made to one side of the electrode frame.
5
ACS Paragon Plus Environment
ACS Energy Letters 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Figure 1. (a) J-V curve and in the inset: steady-state PCE of the champion tandem device on 16 cm2. (b) EQE for the corresponding device (black), for the perovskite top cell (blue), and for the silicon bottom cell (red). Simulated voltage drops across the cell with (c) new and (d) old metal grid design.8 Preliminary observation on stability is presented in Fig. S1. Reverse-scanned, forward-scanned and steady-state efficiencies were measured after storing the same cell from Fig. 1 for 31 days un-encapsulated at room temperature in N2. A steady-state efficiency of 19.9% was measured which represents 91% of initial efficiency. The efficiency loss is due solely to the drop in FF partly because of an increase in series resistance. Further work is required to understand causes to improve stability of future devices. For future devices, MoO3/spiro-OMeTAD stack need to be replaced with high refractive index inorganic hole transport layer to eliminate undesirable parasitic optical absorptions in the short wavelength range (300 nm to 420 nm). 8 For further scale up to larger area (6” × 6”) and commercial viability, textured PDMS layer can be replaced by thin textured glass and spin-coating process can be replaced with blade coating or spray coating method. In summary, we have demonstrated an efficient perovskite/silicon-homo-junction tandem device with the largest cell area (16 cm2), highest steady-state efficiency (21.8%) and fill factor (78%) for area > 10 cm2 to-date.
Supporting Information The Supporting Information is available free of charge on the ACS Publications website at DOI: XXXX Table summarising demonstrated monolithic 2-terminal perovskite/silicon tandems. Experimental section. J-V data for champion tandem device after 31 days of storage.
6
ACS Paragon Plus Environment
Page 6 of 8
Page 7 of 8 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
ACS Energy Letters
Author contributions A. H-B. and J. Z. conceived and designed all the experimental work. J. Z.and H. M. were involved in tandem device fabrications. J. Z performed measurements. F-J. M. contributed to the simulations. The manuscript was written by J. Z. and A. H-B. All authors contributed to the discussion of the results. The overall project was supervised by M. G., S. H. and A. H-B.
Conflicts of interest There are no conflicts to declare.
Acknowledgments The Australian Centre for Advanced Photovoltaics (ACAP) encompasses the Australian-based activities of the Australia-US Institute for Advanced Photovoltaics (AUSIAPV) and is supported by the Australian Government through the Australian Renewable Energy Agency (ARENA). This project is also supported by ARENA via the project 2014 RND075.
References (1) Green, M. A.; Ho-Baillie, A. Perovskite Solar Cells: The Birth of a New Era in Photovoltaics. ACS Energy Lett., 2017, 2, 822-830. (2) Green, M. A. Commercial Progress and Challenges for Photovoltaics. Nat. Energy,
2016, 1(1), 15015. (3) Ho-Baillie A. Perovskites Cover Silicon Textures. Nat. Mater., 2018, 17, 751-752.
7
ACS Paragon Plus Environment
ACS Energy Letters 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
(4) Oxford PV (25 June 2018), Retrieved from https://www.oxfordpv.com/news/oxford-pv-sets-world-record-perovskite-solar-cell. (5) Sahli, F.; Werner, J.; Kamino, B. A.; Brauninger, M.; Monnard, R.; Paviet-Salomon, B.; Barraud, L.; Ding, L.; Diaz Leon, J. J.; Sacchetto, D.; et al. Fully Textured Monolithic Perovskite/Silicon Tandem Solar Cells With 25.2% Power Conversion Efficiency. Nat. Mater., 2018, 17, 820-826. (6) Yoshikawa, K.; Kawasaki, H.; Yoshida, W.; Irie, T.; Konishi, K.; Nakano, K.; Uto, T.; Adachi, D.; Kanematsu, M.; Uzu, H. Silicon Heterojunction Solar Cell with Interdigitated Back Contacts for a Photoconversion Efficiency over 26%. Nat. Energy,
2017, 2(5), 17032. (7) Sahli, F.; Kamino, B. A.; Werner, J.; Bräuninger, M.; Paviet-Salomon, B.; Barraud, L.; Monnard, R.; Seif, J. P.; Tomasi, A.; Jeangros, Q.; et al. Improved Optics in Monolithic Perovskite/Silicon Tandem Solar Cells with a Nanocrystalline Silicon Recombination Junction. Adv. Energy Mater., 2017, 8 , 1701609. (8) Zheng, J.; Lau, C. F. J.; Mehrvarz, H.; Ma, F.-J.; Jiang, Y.; Deng, X.; Soeriyadi, A.; Kim, J.; Zhang, M.; Hu, L.; et al. Large Area Efficient Interface Layer Free Monolithic Perovskite/Homo-Junction-Silicon Tandem Solar Cell with over 20% Efficiency. Energy Environ. Sci., 2018, Doi: 10.1039/c8ee00689j.
8
ACS Paragon Plus Environment
Page 8 of 8
