Abstract
AbstractAll‐perovskite multijunction photovoltaics, combining a wide‐bandgap (WBG) perovskite top solar cell (EG ≈1.6–1.8 eV) with a low‐bandgap (LBG) perovskite bottom solar cell (EG < 1.3 eV), promise power conversion efficiencies (PCEs) >33%. While the research on WBG perovskite solar cells has advanced rapidly over the past decade, LBG perovskite solar cells lack PCE as well as stability. In this work, vacuum‐assisted growth control (VAGC) of solution‐processed LBG perovskite thin films based on mixed Sn–Pb perovskite compositions is reported. The reported perovskite thin films processed by VAGC exhibit large columnar crystals. Compared to the well‐established processing of LBG perovskites via antisolvent deposition, the VAGC approach results in a significantly enhanced charge‐carrier lifetime. The improved optoelectronic characteristics enable high‐performance LBG perovskite solar cells (1.27 eV) with PCEs up to 18.2% as well as very efficient four‐terminal all‐perovskite tandem solar cells with PCEs up to 23%. Moreover, VAGC leads to promising reproducibility and potential in the fabrication of larger active‐area solar cells up to 1 cm2.
Highlights
Enormous interest in perovskite-based multi-junction photovoltaics (PV).[1]
Vacuum-assisted growth control (VAGC) of solution-processed go beyond Shockley–Queisser radiative efficiency limit for single-junction solar cells, wide-bandgap (WBG) perovskite top solar cells (EG > 1.6 eV)[5] are combined with high-efficiency low-bandgap (LBG) bottom solar cells made from Si,[6]
While tandem PV technologies based on market-dominant crystalline Si and CIGS bottom solar cells have recently demonstrated power conversion efficiencies (PCEs) exceeding 28%,[6,11] all-perovskite tandem solar cells are still less advanced
Summary
18.2% (SPCE of 17.1%) under AM 1.5G solar illumination and 4.5% SPCE by using the semitransparent regular-bandgap. The semitransparent regular-bandgap perovskite solar cell with normal architecture provides 18.5% (and SPCE of 17.3%) PCE (Figure 4b,c). The reflectance and transmittance of the regular bandgap as well as EQE of the semitransparent regular bandgap top solar cell and LBG bottom solar cell with and without the semitransparent regular bandgap top solar cell as a filter are shown in Figure S9e,f (Supporting Information) These results demonstrate the potential of VAGC in the reproducible fabrication of high efficiency LBG perovskite solar cells as well as an efficient 4T all-perovskite tandem solar cell. In this work, high-quality LBG perovskite thin films are prepared by VAGC These films demonstrate large columnar grains compared to the reference devices prepared by the conventional antisolvent method. Making use of the LBG PSC (EG ≈ 1.27 eV) developed in this work, a 4T allperovskite tandem solar cell with a reverse J–V PCE as high as 23% is demonstrated
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