Sci. J. We began the fabrication of the SP triple-junction devices by designing and processing a semitransparent series-connected double-junction solar cell, as shown in Fig. In other words, photons of red, yellow and blue light and some near-infrared will contribute to power production, whereas radio waves, microwaves, and most infrared photons will not. The power conversion efficiency (PCE) of a single-junction photovoltaic cell is fundamentally constrained by the ShockleyQueisser limit1. 3a). Prog. Using a more accurate spectrum may give a slightly different optimum. However, due to finite temperature, optical excitations are possible below the optical gap. 16.8% Monolithic all-perovskite triple-junction solar cells via a universal two-step solution process, The role of the third component in ternary organic solar cells, The Influence of Solar Spectrum and Concentration Factor on the Material Choice and the Efficiency of Multijunction Solar Cells, Efficient two-terminal all-perovskite tandem solar cells enabled by high-quality low-bandgap absorber layers, High fabrication yield organic tandem photovoltaics combining vacuum- and solution-processed subcells with 15% efficiency, Perovskiteorganic tandem solar cells with indium oxide interconnect, Opportunities and challenges for tandem solar cells using metal halide perovskite semiconductors, Charge carrier-selective contacts for nanowire solar cells, Next-generation applications for integrated perovskite solar cells, http://creativecommons.org/licenses/by/4.0/, Impact of Operating Temperature and Solar Concentration on the Conversion Efficiency of InGaP/InGaAs/Ge Hybrid Triple-Junction Solar Cell, Mixed 2D-DionJacobson/3D Sn-Pb alloyed perovskites for efficient photovoltaic solar devices, Bidirectional photocurrent in pn heterojunction nanowires, Observation of mixed types of energy gaps in some IIVI semiconductors nanostructured films: towards enhanced solar cell performance, The fabrication of color-tunable organic light-emitting diode displays via solution processing. 22, E77E80 (2010) . Normally these are provided through an electrode on the back surface of the cell. The Shockley-Queisser limit can be exceeded by tandem solar cells, concentrating sunlight onto the cell, and other methods. Sci. Optimal Location of the Intermediate Band Gap Energy in the Intermediate Band Solar Cell : John Wiley & Sons, 2011. Slider with three articles shown per slide. This is a feasible approach as there are indeed several types of far NIR semiconductors like organic donors10,11 and quantum dots12,13 with an extended absorption beyond 1,000nm. 3.1.1 Terminology 30. A cross-sectional transmission electron microscopy (TEM) image of a SP triple-junction solar cell is shown in Fig. But for high illumination, m approaches 1. The conventional series-connected multi-junction cells are most successful in permanently enhancing the record efficiencies of the respective solar technologies2. ] 1c), parallel/series (PS, Supplementary Fig. 7). The calculated bandgap required for the semiconductor to achieve the Shockley-Queisser limit is 1.34 eV , which is higher than the average band gap of perovskite materials. A factor fc gives the ratio of recombination that produces radiation to total recombination, so the rate of recombination per unit area when V=0 is 2tcQc/fc and thus depends on Qc, the flux of blackbody photons above the band-gap energy. The purpose of this study is to determine the optimum location for intermediate band in the middle of band gap of an ideal solar cell for maximum performance. Song, M. et al. The outcome of the simulations is shown in Fig. The most energy efficient ones are those with the lowest amount of spectrum loss. If the resistance of the load is too high, the current will be very low, while if the load resistance is too low, the voltage drop across it will be very low. The hybrid triple-junction solar cell was assembled by stacking a series-connected opaque DPPDPP as back subcell with a semitransparent perovskite device as front subcell. All the materials were used as received without further purification. c When there is a load, then V will not be zero and we have a current equal to the rate of generation of pairs due to the sunlight minus the difference between recombination and spontaneous generation: The open-circuit voltage is therefore given (assuming fc does not depend on voltage) by. . and N.G. Q Currently, the efficiency of our SP triple-junction devices is mainly limited by the mismatch of the VOC of the top subcell with the VOC of the bottom series-connected tandem subcells. Am. Energy Mater. J. Institute of Materials for Electronics and Energy Technology (i-MEET), Friedrich-Alexander University Erlangen-Nrnberg, Martensstrasse 7, Erlangen, 91058, Germany, Fei Guo,Ning Li,Nicola Gasparini,Cesar Omar Ramirez Quiroz,Carina Bronnbauer,Yi Hou,Karen Forberich&Christoph J. Brabec, Bavarian Center for Applied Energy Research (ZAE Bayern), Haberstrasse 2a, Erlangen, 91058, Germany, Erlangen Graduate School in Advanced Optical Technologies (SAOT), Friedrich-Alexander-University Erlangen-Nrnberg, Paul-Gordan-Str. Commun. We chose a diketopyrrolopyrrole-based low bandgap polymer pDPP5T-2 (abbreviated as DPP) blended with [6,6]-phenyl-C61-butyric acid methyl ester (PC60BM) as the photoactive layer of the two front subcells16,17, because the main absorption of this heterojunction extends to the near-infrared range with an absorption minimum between 450 and 650nm (Supplementary Fig. When an electron is ejected through photoexcitation, the atom it was formerly bound to is left with a net positive charge. In contrast to the series-connection, a parallel-connection does not require current matching but instead voltage matching. Mater. c Nat. Nano Lett. The authors derive the equation, which can be solved to find zm, the ratio of optimal voltage to thermal voltage. [9]), The rate of generation of electron-hole pairs not due to incoming sunlight stays the same, so recombination minus spontaneous generation is, I PC60BM (99.5%) and PC70BM (99%) were purchased from Solenne BV. (b) Three-dimensional efficiency map of the SS triple-junction devices as a function of the absorbers bandgaps (Eg) of the three subcells. and Y.H. 5a, illustrating the interplay of the photocurrent generation in the three subcells. Dyes, rare-earth phosphors and quantum dots are actively investigated for fluorescent downshifting. High fill factors up to 68% without resistive losses are achieved for both organic and hybrid triple-junction devices. Phys. Transmittance spectra of the intermediate layers and semitransparent devices were measured using a UVvis-NIR spectrometer (Lambda 950, from Perkin Elmer). Adv. 4b. (A) Breakdown of the different loss processes leading to the band gap-dependent Shockley-Queisser limit for single junction solar cells (out, dark blue). "Chapter 4: Theoretical Limits of Photovoltaic Conversion and New-generation Solar Cells." The hybrid triple-junction device perovskite/DPPDPP exhibits a high current density of 18.51mAcm2 with about 2mAcm2 contributed from the back DPPDPP subcells. 6, 31503170 (2013) . III45019, respectively.) Designing Heterovalent Substitution with Antioxidant Attribute for HighPerformance SnPb Alloyed Perovskite Solar Cells Eventually enough will flow across the boundary to equalize the Fermi levels of the two materials. They used blackbody radiation . {\displaystyle I_{0}=2qt_{c}Q_{c}/f_{c}. Trupke, T. & Wurfel, P. Improved spectral robustness of triple tandem solar cells by combined series/parallel interconnection. 6:7730 doi: 10.1038/ncomms8730 (2015). Series/parallel triple-junction cells with organic, as well as perovskite-based subcells may become a key technology to further advance the efficiency roadmap of the existing photovoltaic technologies. Energy Environ. The semitransparent perovskite device shows a JSC=16.28mAcm2, VOC=0.94V and FF=65.6%, yielding a PCE of 10.04%. Guo, F. et al. The semitransparent perovskite (mixed halide CH3NH3PbI3xClx) solar cells with a device structure of ITO/PEDOT:PSS/Perovskite/PC60BM/ZnO/AgNWs (Supplementary Fig. The key photovoltaic parameters are listed in Table 2. Nature Communications (Nat Commun) (a) Device architecture of the SP triple-junction solar cell. To obtain Taking the photocurrent of the top subcell PCDTBT:PC70BM into consideration, the resulting contour plot of the current density distribution of the entire triple-junction solar cells as a function of the thicknesses of two DPP:PC60BM layers is depicted in Fig. = and V.V.R. The curve is wiggly because of IR absorption bands in the atmosphere. Shockley and Queisser call the ratio of power extracted to IshVoc the impedance matching factor, m. (It is also called the fill factor.) Science 317, 222225 (2007) . Accordingly, the SP interconnection provides a more feasible approach to reach its theoretical efficiency limit. It was first calculated by William Shockley and Hans-Joachim Queisser at Shockley Semiconductor in 1961, giving a maximum efficiency of 30% at 1.1 eV. K.F. Mater. Shockley and Queisser say 30% in their abstract, but do not give a detailed calculation. Kojima, A., Teshima, K., Shirai, Y. We have, therefore, additionally introduced a thin N-PEDOT layer between the ZnO and AgNWs to realize the second intermediate layer consisting of ZnO/N-PEDOT/AgNWs (second intermediate layer). Mater. 2c, the as-prepared opaque tandem device with evaporated Ca/Ag top electrode (15nm/100nm) shows a fill factor (FF) of 64.3% along with a VOC of 1.1V being the sum of two single-junction reference cells (Table 1). Photovoltaics 23, 19 (2015) . In contrast to smaller gap perovskite devices that perform fairly close to their internal Shockley-Queisser limit, wide gap versions show substantial deficits. Cite this article. Prog. The scale bar, 400nm. F.G., N.L. V.V.R., V.R.R. Therefore, many high-performance semiconductors with high external quantum efficiency (EQE) in the NIR absorption range exhibit limited applicability for multi-junction operation, as the perfectly matching semiconductor for the front or back subcells is missing. In combination with our previous findings that the as-designed intermediate layer was able to resist high boiling-point solvent rinsing (chlorobenzene and dichlorobenzene)16, we expect that the successively established two intermediate layers are capable of coupling the series- and parallel-connected three cells into a monolithically deposited triple-junction stack. Energy Mater. Am. A detailed limit calculation for these cells with infinite bands suggests a maximum efficiency of 77.2%[18] To date, no commercial cell using this technique has been produced. These factors include the relative cost per area of solar cells versus focusing optics like lenses or mirrors, the cost of sunlight-tracking systems, the proportion of light successfully focused onto the solar cell, and so on. Luque, Antonio, and Antonio Mart. However, commonly used tin-based narrow-bandgap perovskites have shorter carrier diffusion lengths and lower absorption coefficient than lead- To guarantee the incident light to be able to illuminate on all the three electrodes with an overlapped active area, during the JV measurement a mask with an aperture of 4.5mm2 was used to define the cell area. Energy Mater. A single material can show dierent eective bandgap, set by its absorption spectrum, which depends on its photonic structure. Nat. where Vs is the voltage equivalent of the temperature of the sun. The factor of 2 was included on the assumption that radiation emitted by the cell goes in both directions. Taking Kirchhoffs law into consideration, these circumstances lead to the VOC values of our triple-junction cells close to the top subcells which exhibited lower VOC. The sunlight intensity is a parameter in the ShockleyQueisser calculation, and with more concentration, the theoretical efficiency limit increases somewhat. For example, a planar thermal upconverting platform can have a front surface that absorbs low-energy photons incident within a narrow angular range, and a back surface that efficiently emits only high-energy photons. Simultaneously, optical simulations based on the transfer matrix formalism were carried out to calculate the current generation in the individual subcells34,35, which can provide valuable guidance for optimization of our SP triple-junction devices. (c) Typical JV curves of the single-junction DPP reference cell, tandem DPPDPP reference cell and the semitransparent tandem DPPDPP cell with AgNW top electrode. If, however, the intense light heats up the cell, which often occurs in practice, the theoretical efficiency limit may go down all things considered. The average transmittance of 94.2% in the range of 350850nm ensures minimal optical losses from these interface layers. Figure 4a shows the schematic illustration of the SP triple-junction cell design, where the bottom series-connected tandem subcells in a normal structure are electrically connected in parallel with the top inverted subcell. The SP and PS configurations are distinguished by the stacking sequence of the two interconnections (parallel and series) depending on which interconnection the light passes through first. The author has contributed to research in topic(s): Solar cell & Solar cell research. From a practical point of view, however, the PP interconnection is too complex to process due to the necessity of introducing two transparent intermediate electrodes. The JSC values of the top subcells were verified with EQE measurement (Supplementary Fig. Semonin, O. E. et al. J. Appl. On top of the dried PEDOT:PSS, the first photoactive layer consisting of DPP and PC60BM (1:2 wt.% dissolved in a mixed solvent of chloroform and o-dichlorobenzene (9:1 vol.%)) was deposited at 45C to obtain a thickness of 50nm. ), The rate of generation of electron-hole pairs due to sunlight is. Further, we believe that the novel, but generic, concept demonstrated in this work potentially provides a promising avenue to approach or exceed the ShockleyQueisser limit of many of the currently available high-performance semiconductors such as crystalline silicon, CdTe and perovskite solar cells42,43,44.