Efficient Near-Infrared-Transparent Perovskite Solar Cells Enabling Direct Comparison of 4-Terminal and Monolithic Perovskite/Silicon Tandem Cells

Abstract

Combining market-proven silicon solar cell technology with an efficient wide band gap top cell into a tandem device is an attractive approach to reduce the cost of photovoltaic systems. For this, perovskite solar cells are promising high-efficiency top cell candidates, but their typical device size (<0.2 cm 2 ), is still far from standard industrial sizes. We present a 1 cm 2 near-infrared transparent perovskite solar cell with 14.5% steadystate efficiency, as compared to 16.4% on 0.25 cm 2 . By mechanically stacking these cells with silicon heterojunction cells, we experimentally demonstrate a 4-terminal tandem measurement with a steady-state efficiency of 25.2%, with a 0.25 cm 2 top cell. The developed top cell processing methods enable the fabrication of a 20.5% efficient and 1.43 cm 2 large monolithic perovskite/silicon heterojunction tandem solar cell, featuring a rear-side textured bottom cell to increase its near-infrared spectral response. Finally, we compare both tandem configurations to identify efficiency-limiting factors and discuss the potential for further performance improvement.

Transparent Electrodes for Efficient Optoelectronics

“…[23] For example, the optical band gap (E g ) of sputtered ITO, IZO and IO:H films are between 3.5 and 3.8 eV. [111] Transparent electrodes with low absorptance in the NIR-IR part of the spectrum (transparent electrodes with low FCA) are required for CIGS, SHJ and multi-junction devices, such as perovskite-onsilicon [109,112] and perovskite-on-CIGS [113] tandem solar cells, as these devices employ optical absorbers that are active in this range of the spectrum. These tandem approaches are new highefficiency photovoltaic technologies, with a potential to reach about 30% efficiency, [114,115] clearly underscoring the critical importance and urgency of designing transparent electrodes with exceptionally large broadband transparency.…”

“…2017, 1600529 www.advancedsciencenews.com Figure 2. a) AM1.5G 1 sun irradiance spectra and b) quantum efficiency of a perovskite, [108] CdTe, [95] CIGS, [95] perovskite-SHJ tandem, [109] and SHJ [110] solar cells as a function of wavelength. The absorptance curve of different transparent electrodes measured on glass is also shown for comparison of the relevant wavelength range to be taken into account when developing transparent electrodes for solar cells.…”

Efficient Semitransparent Perovskite Solar Cells Using a Transparent Silver Electrode and Four-Terminal Perovskite/Silicon Tandem Device Exploration

“…For the four-terminal perovskite/ Si devices assembled by a perovskite top cell and Si bottom cell, many efforts were dedicated to search for an appropriate transparent electrode to replace the opaque metal rear contact normally used in PSCs. In most reports [17][18][19][20][21][22][23][24][25][26], the sputtered transparent-conductive-oxide (especially ITO) rear electrode has been commonly used, and the record overall efficiency of 26.4% has been achieved in the four-terminal devices with the perovskite top cell using the ITO/Au-finger electrode [18]. However, the sputtered ITO without postannealing (>200°C) treatment usually shows the suboptimal conductivity, and the high kinetic energy of sputtered particles tends to damage the underlying spiro-OMeTAD or fullerene layers [19]; thus, it is essential to increase the thickness (or add the finger electrodes) to compensate the resistive loss and deposit the buffer layer to protect the organic charge transport layers [18,20].…”

Solution-processed chalcopyrite–perovskite tandem solar cells in bandgap-matched two- and four-terminal architectures

“…16,17,[29][30][31][32] Several tandem devices with HP top cells and Si bottom cells have been reported to date with PCEs up to 25.2% for four-terminal and 21.2% for monolithic devices. [32][33][34] But while these efficiencies are very exciting, the use of silicon for the bottom cell imposes restrictions due to silicon's relatively high bandgap of 1.14 eV, limitation to rigid substrates due to the use of monocrystalline Si wafers, and high fabrication cost of the latter. Recently, solutionprocessed HP/HP tandems have been reported with notable efficiencies up to 20.3% and 17.0% for four-terminal and twoterminal tandems, respectively.…”