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However, one distinct drawback of the series-connected configuration is the stringent current-matching criterion, which requires careful bandgap engineering in combination with an excellent control of the thicknesses of the respective subcells. J. Appl. A generic concept to overcome bandgap limitations for designing highly efficient multi-junction photovoltaic cells. Contribute to chinapedia/wikipedia.en development by creating an account on GitHub. & Wurfel, P. Improving solar cell efficiencies by up-conversion of sub-band-gap light. 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. Phys. . Energy Environ. When an electron is ejected through photoexcitation, the atom it was formerly bound to is left with a net positive charge. Article Here, we explore how thin-film photovoltaic materials with different bandgaps, absorption properties, and thicknesses, perform as IPV devices. A., Roman, L. S. & Inganas, O. They are very expensive to produce, using techniques similar to microprocessor construction but with "chip" sizes on the scale of several centimeters. f 0 Illumination was provided by a solar simulator (Oriel Sol 1 A from Newport) with AM1.5G spectrum and light intensity of 100mWcm2, which was calibrated by a certified silicon solar cell. Mater. Kim, J. Y. et al. Phys. Hirst, L. C. & Ekins-Daukes, N. J. Absorption of a photon creates an electron-hole pair, which could potentially contribute to the current. : John Wiley & Sons, 2011. gratefully acknowledge the financial support through the Aufbruch Bayern initiative of the state of Bavaria. We propose to deposit a transparent counter electrode and parallel-connect these semitransparent high-efficiency cells with one or more deep NIR sensitizers as back subcells. MRS Bull. 7, 399407 (2014) . Chem. Green, M. A., Emery, K., Hishikawa, Y., Warta, W. & Dunlop, E. D. Solar cell efficiency tables (Version 45). Since the act of moving an electron from the valence band to the conduction band requires energy, only photons with more than that amount of energy will produce an electron-hole pair. 10.5% efficient polymer and amorphous silicon hybrid tandem photovoltaic cell. 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. Thermalization of photoexcited carriers with energies in excess of the bandgap limits the power conversion efficiency (PCE) 1, requiring semiconductor absorbers with longer visible-wavelength . The majority of tandem cells that have been produced to date use three layers, tuned to blue (on top), yellow (middle) and red (bottom). 5) and the values calculated by integrating the EQE curve with standard AM1.5 G spectrum show a good agreement with the measured JSC values. In a tandem cell conguration constructed from a single material, one can achieve two dierent eective bandgaps, thereby exceeding the ShockleyQueisser limit. Commun. Tang, J. et al. You are using a browser version with limited support for CSS. Shockley and Queisser calculate Qc to be 1700 photons per second per square centimetre for silicon at 300K. & Blom, P. W. M. Device operation of organic tandem solar cells. Adv. The most widely explored path to higher efficiency solar cells has been multijunction photovoltaic cells, also known as "tandem cells". Note that the strongest top band (indicated by arrow) in the sulphur map belongs to molybdenum because of overlapping of S-K (2.307keV) and Mo-L (2.293keV) lines. In 1961, Shockley and Queisser developed a theoretical framework for determining the limiting efficiency of a single junction solar cell based on the principle of detailed balance equating the. performed the optical simulations. ), The rate of generation of electron-hole pairs due to sunlight is. In cases where outright performance is the only consideration, these cells have become common; they are widely used in satellite applications for instance, where the power-to-weight ratio overwhelms practically every other consideration. For example, one photon with more than double the bandgap energy can become two photons above the bandgap energy. V 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. 136, 1213012136 (2014) . The authors declare no competing financial interests. For series-connected tandem solar cells, the essential component is to construct an efficient intermediate layer serving as charge recombination zone for electrons and holes generated from subcells6,18,19,20,21,22,23,24,25. Optimal Location of the Intermediate Band Gap Energy in the Intermediate Band Solar Cell F.G., N.L. 6) gives a current density of 15.98mAcm2 which is in good agreement with the simulation values (Supplementary Methods for fabrication details). The incident solar spectrum is approximated as a 6000 K blackbody spectrum. 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. This is a very small effect, but Shockley and Queisser assume that the total rate of recombination (see below) when the voltage across the cell is zero (short circuit or no light) is proportional to the blackbody radiation Qc. In our SP triple-junction devices, the top cell is connected in parallel with the bottom series-tandem cell which gives a VOC of 1.1V. To match the voltage between the parallel-connected components and thereby maximize the overall efficiency, a top cell with a VOC value identical or close to the VOC of the bottom series-tandem cell is desired. J. The sunlight intensity is a parameter in the ShockleyQueisser calculation, and with more concentration, the theoretical efficiency limit increases somewhat. Triple junction polymer solar cells. A typical current density versus voltage (JV) characteristic of the as-prepared semitransparent tandem solar cells (Fig. The EQE measurement of a prepared semitransparent perovskite cell (Supplementary Fig. 2b. Photonics 8, 506514 (2014) . 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. Sci. Beneath it is a lower-bandgap solar cell which absorbs some of the lower-energy, longer-wavelength light. 2b) and a sheet resistance of 10sq1, which is comparable to commonly used ITO electrodes. Efficient tandem polymer solar cells fabricated by all-solution processing. Appl. The transmittance spectrum of ZnO/N-PEDOT, the first intermediate layer, is depicted in Fig. Soc. Energy Environ. J. Appl. The record efficiencies of few solar technologies, such as single-crystal silicon, CuInGaSe2, CdTe and GaAs solar cells are constantly shrinking the gap to their fundamental efficiency limits2. Materials with higher electron (or hole) mobility can improve on silicon's performance; gallium arsenide (GaAs) cells gain about 5% in real-world examples due to this effect alone. The JSC values of the top subcells were verified with EQE measurement (Supplementary Fig. The record efficiencies of several types of solar technologies are held by series-connected tandem configurations. Eventually enough will flow across the boundary to equalize the Fermi levels of the two materials. Li, N. et al. The second active layer DPP:PC60BM with thickness of 80nm was then coated on top of N-PEDOT at 55C. Kim, T. et al. / Afterwards, ZnO and N-PEDOT were again deposited onto the second DPP:PC60BM layer using the same coating parameters as for the first deposition. Normally these are provided through an electrode on the back surface of the cell. Mater. Peak external photocurrent quantum efficiency exceeding 100% via MEG in a quantum dot solar cell. where Electron. Prog. 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. 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. Junke Wang, Valerio Zardetto, Ren A. J. Janssen, Nicola Gasparini, Alberto Salleo, Derya Baran, Daniel N. Micha & Ricardo T. Silvares Junior, Xiaozhou Che, Yongxi Li, Stephen R. Forrest, Tomas Leijtens, Kevin A. Bush, Michael D. McGehee, Sebastian Z. Oener, Alessandro Cavalli, Erik C. Garnett, Abdulaziz S. R. Bati, Yu Lin Zhong, Munkhbayar Batmunkh, Nature Communications By changing the location of the intermediate band, output current and therefore performance can be changed. Google Scholar. (At that value, 22% of the blackbody radiation energy would be below the band gap.) We chose silver nanowires (AgNWs) as the intermediate electrode for our triple-junction devices because of their high transparency and low sheet resistance as well as the facile solution processability26,27,28,29,30. Taking advantage of the fact that parallel-connection does not require current matching, and therefore balancing the current flow in the bottom series-tandem DPPDPP cells is of critical significance. Chem. Photonics 6, 180185 (2012) . C.J.B., F.G. and N.L. Any energy lost in a cell is turned into heat, so any inefficiency in the cell increases the cell temperature when it is placed in sunlight. 24, 21302134 (2012) . The average transmittance of 94.2% in the range of 350850nm ensures minimal optical losses from these interface layers. These cells use multiple p-n junctions, each one tuned to a particular frequency of the spectrum. 20, 579583 (2008) . ACS Nano 4, 37433752 (2010) . (b) Transmittance spectra of the two intermediate layers used in the SP triple-junction solar cells. 5b. In real parallel-connected solar cells, however, the VOC of the tandem cells can be close either to the subcell with high VOC or to the subcell with low VOC depending on the series resistance of the subcells37. [24], A related concept is to use semiconductors that generate more than one excited electron per absorbed photon, instead of a single electron at the band edge. The first intermediate layers, ZnO and N-PEDOT:PSS, were sequentially bladed at 50C and annealed at 80C for 5min in air and the obtained layer thickness for both layers is 35nm. ] The semitransparent perovskite device shows a JSC=16.28mAcm2, VOC=0.94V and FF=65.6%, yielding a PCE of 10.04%. However, commonly used tin-based narrow-bandgap perovskites have shorter carrier diffusion lengths and lower absorption coefficient than lead- ITO-coated glass substrates (2.5 2.5)cm2 with a sheet resistance of 15sq1 were purchased from Weidner Glas and patterned with laser before use. ADS and N.G. CAS B. et al. (A) Breakdown of the different loss processes leading to the band gap-dependent Shockley-Queisser limit for single junction solar cells (out, dark blue). In brighter light, when it is concentrated by mirrors or lenses for example, this effect is magnified. The theory is described by W. Shockley and H. J. Queisser in Journal of Applied Physics 32 (1961). Moreover, as depicted in Fig. Energy Mater. The slightly lower FFs for the devices fabricated on AgNWs as compared with the ITO counterparts can be ascribed to the higher series resistance (RS), probably resulting from the contact resistance between the AgNWs and ZnO. JV curves of all the devices were recorded using a source measurement unit from BoTest. 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. We can clearly see this from the tail of the imaginary dielectric function below the optical gap depending on temperature. A more recent reference gives, for a single-junction cell, a theoretical peak performance of about 33.7%, or about 337 W/m2 in AM1.5.[1][10]. There are several considerations: Any material, that is not at absolute zero (0 Kelvin), emits electromagnetic radiation through the black-body radiation effect. Guo, F. et al. Adebanjo, O. et al. Choosing the best location in terms of solar cell energy gap and how to change . Soc. J. This leads to a higher interest in lowering the bandgap of perovskite. In this way, sunlight creates an electric current.[6]. The work was supported by the Cluster of Excellence Engineering of Advanced Materials (EAM) and the SFB 953 at the University of Erlangen-Nuremberg. We present data for devices that feature a single-tip electrode contact and an array with 24 tips (total planar area of 1 1 m2)capableof generating a current density of 17 mA cm-2 under illumination of AM1.5 G. In summary, the BPVE . For a zoc of 32.4, this comes to 86.5%. Microcavity-enhanced light-trapping for highly efficient organic parallel tandem solar cells. The Shockley-Queisser-limit is a theoretical limit for solar cells. Abstract All-perovskite tandem solar cells are promising for breaking through the single-junction Shockley-Queisser limit, . = The light grey dashed lines indicate the numerical addition of the bottom series-tandem subcells and the top subcell. Recently, indoor photovoltaics have gained research attention due to their potential applications in the Internet of Things (IoT) sector and most of the devices in moder As shown in Fig. Typical JV characteristics of the as-prepared single-junction devices are displayed in Fig. PC60BM (99.5%) and PC70BM (99%) were purchased from Solenne BV. [ & Snaith, H. J. J. Phys. [4] Solution-processed parallel tandem polymer solar cells using silver nanowires as intermediate electrode. 3.1 Introduction 28. 3b,c and the key photovoltaic parameters are summarized in Table 1. On this Wikipedia the language links are at the top of the page across from the article title. (b) Three-dimensional efficiency map of the SS triple-junction devices as a function of the absorbers bandgaps (Eg) of the three subcells. Soc. [23] One system under investigation for this is quantum dots. The middle AgNW layer in this triple-junction device serves as a common cathode to collect electrons created by the subcells. 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. Nano Lett. As the temperature of the cell increases, the outgoing radiation and heat loss through conduction and convection also increase, until an equilibrium is reached. Guo, F. et al. In March 1961, an article entitled Detailed Balance Limit of Efficiency of p-n Junction Solar Cells by William Shockley and Hans Joachim Queisser appeared in the Journal of Applied Physics (Shockley & Queisser, 1961).Following an earlier rejection by the journal (Marx, 2014; Queisser, 2007) and barely noticed for several years after publication, this article has now become an . The scale bar, 200nm. The ratio of the open-circuit voltage to the band-gap voltage Shockley and Queisser call V. Under open-circuit conditions, we have. A cross-sectional transmission electron microscopy (TEM) image of a SP triple-junction solar cell is shown in Fig. c Previous search for low-bandgap (1.2 to 1.4 eV) halide perovskites has resulted in several candidates, but all are hybrid organic-inorganic compositions, raising potential concern regarding . It is used for semiconductors to generate electricity, as a result of solar radiation. 12, 48894894 (2012) . C.O.R.Q., C.B. & Nozik, A. J. The dominant losses responsible for the Shockley-Queisser limit are below band-gap and thermalization (hot carrier) losses; together, they account for >55% of the total absorbed solar energy. Am. V.R.R. (q being the charge of an electron). The ShockleyQueisser limit is calculated by examining the amount of electrical energy that is extracted per photon of incoming sunlight. The product of the short-circuit current Ish and the open-circuit voltage Voc Shockley and Queisser call the "nominal power". Get the most important science stories of the day, free in your inbox. 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. prepared the semitransparent perovskite cells. Organometal halide perovskites have emerged as promising materials that enable fabrication of highly efficient solar cells by solution deposition38,39,40. }, where We would like to thank Cambrios Technology Corporation, Dr Mathieu Turbiez from BASF and Dr Norman Lchinger from Nanograde for the supply of AgNWs, DPP and ZnO dispersion, respectively. Shockley and Queisser say 30% in their abstract, but do not give a detailed calculation. These results demonstrated the excellent functionality of the ZnO/N-PEDOT intermediate layer in the series-connected tandem architecture. Thermal upconversion is based on the absorption of photons with low energies in the upconverter, which heats up and re-emits photons with higher energies. By combining a semitransparent perovskite cell with series-connected DPPDPP cells in parallel, the fabricated hybrid triple-junction devices showed an efficiency improvement by 12.5% compared with the corresponding reference cells. It should be no surprise that there has been a considerable amount of research into ways to capture the energy of the carriers before they can lose it in the crystal structure. (a) Schematic architecture of the semitransparent series-tandem solar cells (DPPDPP) with AgNWs top electrode. Soc. s the bandgap energy Eg=1.4 eV. There are in total four types of device configurations for a triple-junction solar cell, designated as series/series (SS, Fig. 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. The outcome of the calculations showed that maximum efficiencies of 17.29%, 17.89%, 15.41% and 13.95% are achievable for SS, PS, SP and PP configurations, respectively. The record efficiencies of several types of solar. Fei Guo and Ning Li: These authors contributed equally to this work. The hybrid platform offers sunlight-to-electricity conversion efficiency exceeding that imposed by the S-Q limit on the corresponding PV cells across a broad range of bandgap energies, under low optical concentration (1-300 suns), operating temperatures in the range 900-1700 K, and in simple flat panel designs. By integrating series- and parallel-interconnections into a triple-junction configuration, we find significantly relaxed material selection and current-matching constraints. 8, 689692 (2008) . Mater. Secondly, reflectance of the material is non-zero, therefore absorbance cannot be 100% above the band gap. t A solar cell's energy conversion efficiency is the percentage of power converted from sunlight to electrical energy under "standard test conditions" (STC). There is a trade-off in the selection of a bandgap. Together with the high FF of 64.5% and VOC of 0.95V, the hybrid triple-junction device shows a PCE value of 11.34%, corresponding to a PCE enhancement by 12.5%. 4, 1446 (2013) . Adv. q The STEM energy dispersive X-ray spectrometry (EDS) elemental maps (Ag, Zn and S) of the cross-section shown in Fig. Subsequent calculations have used measured global solar spectra, AM 1.5, and included a back surface mirror which increases the maximum solar conversion efficiency to 33.16% for a single-junction solar cell with a bandgap of 1.34 eV. Among them, the multi-junction concept is one of the most promising candidates that allows to simultaneously address the two dominant loss mechanisms4, namely, sub-bandgap transmission and thermalization losses, which account for >55% of the total energy of the solar radiation9. Electrons can be excited by light as well as by heat. To illustrate the benefit of the hybrid triple-junction device, we further theoretically compared the current generation between the single opaque perovskite cells and the hybrid triple-junction devices using the same material combinations. 6, 34073413 (2013) . In a traditional solid-state semiconductor such as silicon, a solar cell is made from two doped crystals, one an n-type semiconductor, which has extra free electrons, and the other a p-type semiconductor, which is lacking free electrons, referred to as "holes." Shockley and Queisser give a graph showing m as a function of the ratio zoc of the open-circuit voltage to the thermal voltage Vc. 3 Optical Modeling of Photovoltaic Modules with Ray Tracing Simulations 27 Carsten Schinke, Malte R.Vogt and Karsten Bothe. Prog. 2b. is the number of photons above the band-gap energy falling on the cell per unit area, and ts is the fraction of these that generate an electron-hole pair. The device structure of the single and tandem reference cells are: Glass/ITO/PEDOT:PSS/DPP:PC60BM/Ca/Ag and Glass/ITO/PEDOT:PSS/DPP:PC60BM/ZnO/N-PEDOT/DPP:PC60BM/Ca/Ag. and C.J.B. Given that the perovskite single cell (mixed halide CH3NH3PbI3xClx) provides a high VOC of 1V, which is comparable to our series-connected DPPDPP cells, it is straightforward to fabricate a PS connected triple-junction device by placing a DPPDPP cell behind a semitransparent perovskite cell, and thereby adding up the total current density for the hybrid triple-junction device. & Peumans, P. Solution-processed metal nanowire mesh transparent electrodes. By submitting a comment you agree to abide by our Terms and Community Guidelines. They also can be used in concentrated photovoltaic applications (see below), where a relatively small solar cell can serve a large area. 5, 91739179 (2012) . BC8 . These cells require the use of semiconductors that can be tuned to specific frequencies, which has led to most of them being made of gallium arsenide (GaAs) compounds, often germanium for red, GaAs for yellow, and GaInP2 for blue. Meanwhile, the conduction-band electrons are moving forward towards the electrodes on the front surface. Second, the VOC of the back cell, which is consisting of a series-connection of deep NIR absorbers, can be custom fabricated by stacking an arbitrary sequence of semiconductors with different bandgaps in series. In silicon the conduction band is about 1.1 eV away from the valence band, this corresponds to infrared light with a wavelength of about 1.1microns. On the cleaned substrates, PEDOT:PSS (Clevious P VP Al 4083, 1:3 vol.% diluted in isopropanol) was firstly bladed and annealed at 140C for 5min to obtain a layer thickness of 40nm. These photons will pass through the solar cell without being absorbed by the device. Energy Environ. Dennler, G. et al. Use the Previous and Next buttons to navigate the slides or the slide controller buttons at the end to navigate through each slide. of states. Shockley and Queisser's work considered the most basic physics only; there are a number of other factors that further reduce the theoretical power. The Shockley-Queisser limit can be exceeded by tandem solar cells, concentrating sunlight onto the cell, and other methods. 1 Sunlight can be concentrated with lenses or mirrors to much higher intensity. Zuo, L. J. et al. As a consequence, the net photocurrent gain contributed by the deep NIR subcells ultimately adds up to the overall photocurrent of the multi-junction photovoltaic cell. 172054 and No. 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. 44, 75327539 (2005) . Am. In combination with the still high FF of 63.0%, these results provide sufficient evidence that the solution-deposited AgNW meshes are highly compatible with the underlying layers without compromising the device performance. Nat. This relies on a practical IR cell being available, but the theoretical conversion efficiency can be calculated. 2a. (a) Device architecture of the SP triple-junction solar cell. Figure 6b shows the measured JV curves of the experimentally constructed hybrid triple-junction solar cell and the corresponding subcells. For our SP triple-junction organic solar cells, with the exception of bottom ITO-coated glass substrate and top evaporated MoOX/Ag electrode, all the layers were sequentially deposited using a doctor blade in ambient atmosphere. Noticeably, from Table 2 we can see that the measured photocurrents of the triple-junction cells are more or less identical to the sum JSC values extracted from the respective bottom DPPDPP subcells and top PCDTBT or OPV12 subcells. 6:7730 doi: 10.1038/ncomms8730 (2015). Note that in these two simulations the top PCDTBT:PC70BM layer thickness is fixed to 80nm, corresponding to the optimized thickness in their single-junction state. Chalcogenophene comonomer comparison in small band gap diketopyrrolopyrrole-based conjugated polymers for high-performing field-effect transistors and organic solar cells. c However, due to finite temperature, optical excitations are possible below the optical gap. Shockley and Queisser calculated that the best band gap for sunlight happens to be 1.1 eV, the value for silicon, and gives a u of 44%. Prog. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate. Herein, we chose ZnO and neutral PEDOT:PSS (N-PEDOT) as the N- and P-type charge extraction materials, respectively, because the work functions of the two materials match well with the energy levels of the donor DPP and acceptor PC60BM20,23. 16, 141149 (2008) . The liftout sample was prepared using a focused ion beam (FIB, FEI Helios NanoLab 660) and imaged subsequently with the TITAN3 aberration-corrected TEM. The multi-junction concept is the most relevant approach to overcome the ShockleyQueisser limit for single-junction photovoltaic cells. Article It is worth mentioning that we have employed a simple modified doctor blading technique to coat the AgNW electrode16, which enables the deposition of the NW film in a stripe and thereby eliminates any subsequent patterning steps. This process is known as photoexcitation. Moreover, it should be noted that although our triple-junction cells have achieved PCEs of 5.35 and 5.43%, which are higher than either one of the single-junction reference devices, those values are still 0.4% lower than the sum PCEs of the incorporated subcells. Now, the challenge remains to replace the vacuum-deposited metal electrode with a solution-processed, highly transparent electrode without deteriorating the performance of the established subcells beneath. Article In the most common design, a high-bandgap solar cell sits on top, absorbing high-energy, shorter-wavelength light, and transmitting the rest. To deposit the intermediate electrode, 80-nm-thick AgNWs was bladed onto N-PEDOT at 45C and the resulting NW film showed a sheet resistance of 8sq1. F.W.F. It is obvious that to maximize the use of incident photons, the thicknesses of the two DPP:PC60BM active layers should follow the red dashed line where the photocurrents generated in the two subcells are identical. 4b. The optimum depends on the shape of the I versus V curve. Second ed. (a) Calculated JSC distribution of the three subcells as a function of the back two DPP:PC60BM film thicknesses. V The Schockley-Queisser (SQ) limit is a famous limit on the maximal possible efficiency of solar cells, limited only by fundamental physics. Indeed, independent measurement of the AgNW electrode employed in the current study shows an average visible transmittance of 90% (Fig.