Future high performance PV devices are expected to be tandem cells consisting of a low bandgap bottom cell and a high bandgap top cell. In this study, we developed a cradle-to-end of use life cycle assessment model to evaluate the environmental impacts, primary energy demand (PED), and energy payback time (EPBT) of four integrated two-terminal tandem solar cells composed of either Si bottom and lead-based perovskite (PK Pb ) top cells (Si/PK Pb ), copper indium gallium selenide (CIGS) and PK Pb (CIGS/PK Pb ), copper zinc tin selenide (CZTS) and PK Pb (CZTS/PK Pb ), or tin-lead based perovskite (PK Sn,Pb ) and PK Pb (PK Sn,Pb /PK Pb ). Environmental impacts from single junction Si solar cells were used as a reference point to interpret the results. We found that the environmental impacts for a 1 m 2 area of a cell were largely determined by the bottom cell impacts and ranged from 50% (CZTS/PK Pb ) to 120% of those of a Si cell. The ITO layer used in Si/PK Pb , CZTS/PK Pb , and PK Sn,Pb /PK Pb is the most impactful after the Si and CIGS absorbers, and contributed up to 70% (in PK Sn,Pb /PK Pb ) of the total impacts for these tandem PVs. Manufacturing a single two-terminal device was found to be a more environmentally friendly option than manufacturing two constituent single-junction cells and can reduce the environmental impacts by 30% due to the exclusion of extra glass, encapsulation, front contact and back contact layers. PED analysis indicated that PK Sn,Pb /PK Pb manufacturing has the least energy-intensive processing, and the EPBTs of Si/PK Pb , CIGS/PK Pb , CZTS/PK Pb , and PK Sn,Pb /PK Pb tandems were found to be ∼13, ∼7, ∼2, and ∼1 months, respectively. On an impacts per kW h of Si basis the environmental impacts of all the devices were much higher (up to ∼10 times). These results can be attributed to the low photoconversion efficiency (PCE) and short lifetime that were assumed. While PK Sn,Pb /PK Pb has higher impacts than Si based on current low PCE (21%) and short lifetime (5 years) assumptions, it can outperform Si if its lifetime and PCE reach 16 years and 30%, respectively. Among the configurations considered, the PK Sn,Pb /PK Pb structure has the potential to be the most environmentally friendly technology.
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26.7% Efficient 4-Terminal Perovskite–Silicon Tandem Solar Cell Composed of a High-Performance Semitransparent Perovskite Cell and a Doped Poly-Si/SiOx Passivating Contact Silicon Cell
The rapid rise in single-junction perovskite solar cell (PSC) efficiencies, tunable bandgap and low-cost solution processability make PSCs an attractive candidate for tandems with Si bottom cells. However, the challenge is to fabricate a high-performance semitransparent perovskite top cell in combination with an appropriate silicon bottom cell with high response to long wavelength photons that are filtered through the perovskite top cell. Currently, semitransparent perovskite cells show much lower performance compared to their opaque counterparts while high-performance silicon bottom cells, such as heterojunction with intrinsic thin layer (HIT) and interdigitated back contact (IBC), maybe too expensive to meet the cost and efficiency targets for commercial viability. Here, we demonstrate a 26.7% perovskite-Si four terminal (4T) tandem cell comprising a highly efficient 17.8% CsFAMAPbIBr semitransparent, 1.63-eV bandgap perovskite top cell and a ≥ 22% efficiency n-type Si bottom cell fabricated with a conventional boron diffused emitter on the front and carrier selective n+ poly-Si/SiOx passivated contact on the rear. This is among the highest efficiency perovskite/Si 4T tandems published to-date and represents the first demonstration of the use of the high temperature-resistant single side n-TOPCon Si cell in a 4T configuration.
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- Award ID(s):
- 1665279
- NSF-PAR ID:
- 10134953
- Date Published:
- Journal Name:
- IEEE journal of photovoltaics
- ISSN:
- 2156-3381
- Page Range / eLocation ID:
- 1 to 6
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Wide–band gap metal halide perovskites are promising semiconductors to pair with silicon in tandem solar cells to pursue the goal of achieving power conversion efficiency (PCE) greater than 30% at low cost. However, wide–band gap perovskite solar cells have been fundamentally limited by photoinduced phase segregation and low open-circuit voltage. We report efficient 1.67–electron volt wide–band gap perovskite top cells using triple-halide alloys (chlorine, bromine, iodine) to tailor the band gap and stabilize the semiconductor under illumination. We show a factor of 2 increase in photocarrier lifetime and charge-carrier mobility that resulted from enhancing the solubility of chlorine by replacing some of the iodine with bromine to shrink the lattice parameter. We observed a suppression of light-induced phase segregation in films even at 100-sun illumination intensity and less than 4% degradation in semitransparent top cells after 1000 hours of maximum power point (MPP) operation at 60°C. By integrating these top cells with silicon bottom cells, we achieved a PCE of 27% in two-terminal monolithic tandems with an area of 1 square centimeter.
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Maximizing the power conversion efficiency (PCE) of perovskite/silicon tandem solar cells that can exceed the Shockley-Queisser single-cell limit requires a high-performing, stable perovskite top cell with a wide bandgap. We developed a stable perovskite solar cell with a bandgap of ~1.7 electron volts that retained more than 80% of its initial PCE of 20.7% after 1000 hours of continuous illumination. Anion engineering of phenethylammonium-based two-dimensional (2D) additives was critical for controlling the structural and electrical properties of the 2D passivation layers based on a lead iodide framework. The high PCE of 26.7% of a monolithic two-terminal wide-bandgap perovskite/silicon tandem solar cell was made possible by the ideal combination of spectral responses of the top and bottom cells.
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Abstract: Monolithic integrated thin film tandem solar cells consisting of a high bandgap perovskite top cell and a low bandgap thin film bottom cell are expected to reach higher power conversion efficiencies (PCEs) with lower manufacturing cost and environmental impacts than the market-dominant crystalline silicon photovoltaics. There have been several demonstrations of 4-terminal and 2-terminal perovskite tandem devices with CuInGaSe 2 (CIGS) or CuInSe 2 (CIS) and, similar to the other tandem structures, the optimization of this device relies on optimal choice for the perovskite bandgap and thickness. Therefore, further advancement will be enabled by tuning the perovskite absorber to maximize the photocurrent limited by the current match condition. Here, we systematically study the optical absorption and transmission of perovskite thin films with varying absorber band gap. Based on these results, we model the photocurrent generations in both perovskite and CIS subcells and estimate the performances of projected tandem devices by considering the ideally functioning perovskite and CIS device. Our results show that for perovskite layers with 500 nm thickness the optimal bandgap is around 1.6 eV. With these configurations, PCEs above 20% could be achieved by monolithically integrated perovskite/CIS tandem solar cells. Also by modelling the absorption at every layer we calculate the quantum efficiency at each subcell in addition to tracking optical losses.more » « less
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Abstract Perovskite‐organic tandem solar cells are attracting more attention due to their potential for highly efficient and flexible photovoltaic device. In this work, efficient perovskite‐organic monolithic tandem solar cells integrating the wide bandgap perovskite (1.74 eV) and low bandgap organic active PBDB‐T:SN6IC‐4F (1.30 eV) layer, which serve as the top and bottom subcell, respectively, are developed. The resulting perovskite‐organic tandem solar cells with passivated wide‐bandgap perovskite show a remarkable power conversion efficiency (PCE) of 15.13%, with an open‐circuit voltage (
V oc) of 1.85 V, a short‐circuit photocurrent (J sc) of 11.52 mA cm−2, and a fill factor (FF) of 70.98%. Thanks to the advantages of low temperature fabrication processes and the flexibility properties of the device, a flexible tandem solar cell which obtain a PCE of 13.61%, withV ocof 1.80 V,J scof 11.07 mA cm−2, and FF of 68.31% is fabricated. Moreover, to demonstrate the achieved highV ocin the tandem solar cells for potential applications, a photovoltaic (PV)‐driven electrolysis system combing the tandem solar cell and water splitting electrocatalysis is assembled. The integrated device demonstrates a solar‐to‐hydrogen efficiency of 12.30% and 11.21% for rigid, and flexible perovskite‐organic tandem solar cell based PV‐driven electrolysis systems, respectively.
- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1109/JPHOTOV.2019.2963564
