Large area efficient interface layer free monolithic perovskite/homo-junction-silicon tandem solar cell with over 20% efficiency

Abstract

aMonolithic perovskite/silicon tandem solar cells show great promise for further efficiency enhancement for current silicon photovoltaic technology. In general, an interface (tunnelling or recombination) layer is usually required for electrical contact between the top and the bottom cells, which incurs higher fabrication costs and parasitic absorption. Most of the monolithic perovskite/Si tandem cells demonstrated use a hetero-junction silicon (Si) solar cell as the bottom cell, on small areas only. This work is the first to successfully integrate a low temperature processed (r150 1C) planar CH 3 NH 3 PbI 3 perovskite solar cell on a homo-junction silicon solar cell to achieve a monolithic tandem without the use of an additional interface layer on large areas (4 and 16 cm 2 ).Solution processed SnO 2 has been effective in providing dual functions in the monolithic tandem, serving as an ETL for the perovskite cell and as a recombination contact with the n-type silicon homo-junction solar cell that has a boron doped p-type (p++) front emitter. The SnO 2 /p++ Si interface is characterised in this work and the dominant transport mechanism is simulated using Sentaurus technology computer-aided design (TCAD) modelling. The champion device on 4 cm 2 achieves a power conversion efficiency (PCE) of 21.0% under reverse-scanning with a V OC of 1.68 V, a J SC of 16.1 mA cm À2 and a high FF of 78% yielding a steady-state efficiency of 20.5%. As our monolithic tandem device does not rely on the SnO 2 for lateral conduction, which is managed by the p++ emitter, up scaling to large areas becomes relatively straightforward. On a large area of 16 cm 2 , a reverse scan PCE of 17.6% and a steady-state PCE of 17.1% are achieved. To our knowledge, these are the most efficient perovskite/homo-junction-silicon tandem solar cells that are larger than 1 cm 2 . Most importantly, our results demonstrate for the first time that monolithic perovskite/silicon tandem solar cells can be achieved with excellent performance without the need for an additional interface layer. This work is relevant to the commercialisation of efficient large-area perovskite/homo-junction silicon tandem solar cells. Broader contextA simple approach for integrating a perovskite solar cell monolithically onto a Si solar cell is reported here. The first advantage of this approach is that it does not require additional fabrication of an additional interface layer between the perovskite and Si cell. The second advantage of this approach is that it is compatible with a homo-junction p-n Si solar cell, which is a common Si solar cell structure for commercial cells. The third advantage is that the entire sequence for the planar perovskite cell fabrication is done at low temperatures, minimising damage to the bottom Si solar cell. The fourth advantage is that the SnO 2 electron transport layer of the perovskite top cell also serves as a recombination contact with the silicon bottom cell. Finally, this monolithic tandem approach does not rely on the SnO 2 for lateral conducti...

Grain Engineering for Perovskite/Silicon Monolithic Tandem Solar Cells with Efficiency of 25.4%

“…25,26,[28][29][30][31][32][33][34][35][36][37][38][39] With the improvement in WBG perovskite cells, the efficiencies of perovskite/silicon monolithic tandem solar cells have increased from 13.7% in 2015 to 23.6% in 2017, and to 25.2% in June 2018 (Table S1). [5][6][7][8][9][10][11][12][13][14][15][16][17][18] Optical loss, fill factor loss, current mismatch, and open-circuit voltage (V oc ) deficit (E g /q À V oc ) are the main issues currently limiting the PCE of these perovskite/silicon tandem devices. Several technologies have been explored to reduce the reflection-and parasitic-absorption-induced optical losses, such as antireflective foils, 12 nanocrystalline silicon recombination junctions, 13 silicon-nanoparticle rear reflectors, 11 and double-side-textured silicon bottom cells.…”

“…Due to their solution processability, bandgap tunability, and high photovoltaic performance without epitaxial growth that requires lattice matching, organicinorganic halide perovskites have distinguished themselves from other photovoltaic semiconductors as suitable tandem partners for silicon. [5][6][7][8][9][10][11][12][13][14][15][16][17][18] Recent…”

Two‐Terminal Perovskites Tandem Solar Cells: Recent Advances and Perspectives

“…In addition, to protect the perovskite top‐cell upon post‐annealing, organic PEIE/PCBM bi‐layer instead of conventional TiO 2 was utilized as the ETL. In June 2018, Zheng et al achieved an efficient interface‐layer‐free monolithic perovskite/homo‐junction‐silicon tandem solar cell on large areas (4 and 16 cm 2 ), with a low‐temperature processed SnO 2 serving as both the ETL and recombination layers. The CH 3 NH 3 PbI 3 ‐Si tandem device on 4 cm 2 area showed an efficiency of 21.0%, with V OC of 1.68 V, J SC of 16.1 mA cm −2 and a high FF of 78%.…”

Solution‐Processable Perovskite Solar Cells toward Commercialization: Progress and Challenges

“…Ballif and coworkers reported a 12.96 cm 2 monolithic tandem cell with a steady‐state PCE of 18%, in which a nanocrystalline silicon was employed as the recombination layer instead of transparent conductive oxides to mitigate the optical losses and shunt resistance . Ho‐Baillie et al demonstrated a 16 cm 2 monolithic tandem cell without the use of an additional interface/recombination layer achieving a PCE of 17.1%, and just in few months they pushed the efficiency of 16 cm 2 tandem device to 21.8% by employing a new metal grid design, a mixed perovskite absorber, and a textured rear surface . Despite the spectacular development of monolithic perovskite/silicon tandem cell, the area of the currently largest 16 cm 2 cell lags far behind the size of silicon solar cells of over 200 cm 2 (6 in.).…”