Efficient Inverted Tandem Polymer Solar Cells with a Solution‐Processed Recombination Layer

Kouijzer, S Sandra; Esiner, S Serkan; Frijters, Chm Lilian; Turbiez, Mgr Mathieu; Wienk, MM Martijn; Janssen, Raj René

doi:10.1002/aenm.201100773

Cited by 107 publications

(88 citation statements)

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“…15,16 In addition, the inverted structure also matches well with the vertical phase separation of the active bulk heterojunction layer and thus enhances charge collection at the organic/electrode interfaces. 17,18 Solution processed ZnO nanoparticle (ZnONP) layers are widely used as cathodes for the inverted polymer solar cells 19,20 and n-type side of the recombination layer in tandem architectures 21,22 due to comparatively high electron conductivity, low work function, transparency and environmental stability. The use of ZnO layers is not without problems, however.…”

Section: Introductionmentioning

confidence: 99%

Effects of ultraviolet soaking on surface electronic structures of solution processed ZnO nanoparticle films in polymer solar cells

et al. 2014

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Abstract:We systematically show the effect of UV-light soaking on surface electronic structure and chemical states of solution processed ZnO nanoparticle (ZnONP) films in UHV, dry air and UV-ozone. UV exposure in UHV induces a slight decrease in work function and surfacedesorption of chemisorbed oxygen, whereas UV exposure in presence of oxygen cause an increase in work function due to oxygen atom vacancy filling in the ZnO matrix. We demonstrate that UV-light soaking in combination with vacuum or oxygen can tune the work function of the ZnONP films over a range exceeding 1 eV. Based on photovoltaic performance and diode measurements, we conclude that the oxygen atom vacancy filling occurs mainly at the surface of the ZnONP films and that the films consequently retain their n-type behavior despite significant increase in measured work function.

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Section: Introductionmentioning

confidence: 99%

Effects of ultraviolet soaking on surface electronic structures of solution processed ZnO nanoparticle films in polymer solar cells

et al. 2014

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“…Kouijzer et al [ 36 ] analyzed blends of a small band gap ( E g = 1.46 eV) diketopyrrolopyrrole-quinquethiophene alternating copolymer (PDPP5T) [ 37,38 ] with [6,6]-phenyl-C71-butyric acid methyl ester ([70]PCBM), and suggested that the phase separation in PDPP5T:[70]PCBM blends is due to spinodal liquidliquid (L-L) demixing. In a previous paper, [ 39 ] we have shown how it is possible to use a one-dimensional (1D) drift-diffusion model [ 40 ] to simulate the current-voltage ( J-V ) characteristics of such PDPP5T:[70]PCBM blends, either homogeneous or phase separated.…”

Section: Wileyonlinelibrarycommentioning

confidence: 99%

The Effect of Large Compositional Inhomogeneities on the Performance of Organic Solar Cells: A Numerical Study

Bartesaghi

Koster

2014

Adv Funct Materials

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wileyonlinelibrary.comBHJs. [5][6][7] The length scale of the separation between the donor and the acceptor material is relevant to the processes of generation and transport of free charges. [8][9][10] Also the composition [10][11][12] and the crystallinity [ 13,14 ] of the donor and acceptor domains, and the existence of percolation pathways to extract the photogenerated charges [ 15,16 ] play an important role.Many studies have addressed the possibilities of controlling the morphology by means of the processing conditions. For solution-based processing such as spincoating, doctor blading, slot dye coating or inkjet printing it has been shown that the goal of optimizing the morphology has to be pursued since the preparation of the solution, by choosing the proper solvent, [17][18][19] co-solvents, [ 20,21 ] and additives. [ 22 ] The deposition process [ 23,24 ] and the post-deposition treatments, e. g. thermal [ 25 ] or solvent [ 26 ] annealing, defi ne the fi nal morphology of the active layer.It would be greatly benefi cial for the optimization of BHJs to develop accurate models to predict the morphology based on properties of the materials and processing conditions. Furthermore, a model to accurately relate the morphology of the active layer and the effi ciency of the device [27][28][29][30][31] is essential to orient the optimization process towards the best-performing morphology.Depending on the processing conditions, the deposition of polymer:fullerene blends can result in an homogeneous, fi nely dispersed mixture of polymer and fullerene, or in a phase separated system with large (hundreds of nm), rather pure domains of fullerene embedded into a polymer-rich matrix, similar to the morphology depicted in Figure 1 . This has been observed for many polymer: fullerene systems; [ 10,17,[32][33][34][35] it is therefore interesting to understand how the phase separation in these blends affects the performance.Kouijzer et al. [ 36 ] analyzed blends of a small band gap ( E g = 1.46 eV) diketopyrrolopyrrole-quinquethiophene alternating copolymer (PDPP5T) [ 37,38 ] with [6,6]-phenyl-C71-butyric acid methyl ester ([70]PCBM), and suggested that the phase separation in PDPP5T:[70]PCBM blends is due to spinodal liquidliquid (L-L) demixing. In a previous paper, [ 39 ] we have shown how it is possible to use a one-dimensional (1D) drift-diffusion model [ 40 ] to simulate the current-voltage ( J-V ) characteristics of such PDPP5T:[70]PCBM blends, either homogeneous or phase separated. For the latter case, we treated the total current as the The Effect of Large Compositional Inhomogeneities on the Performance of Organic Solar Cells: A Numerical StudyDavide Bartesaghi and L. Jan Anton Koster * The power conversion effi ciency of solar cells based on a conjugated polymer (donor) and a fullerene derivative (acceptor) is very sensitive to the morphology of the active layer. One detrimental feature, which is often encountered in non-optimal morphologies, is the occurrence of fullerene blobs in a fi nely mixed matrix containing b...

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“…Currently, combinations of p-type metallic poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and n-type semiconducting metal oxides (e.g., zinc oxide (ZnO) or titanium sub-oxide (TiO x )) are widely used in RLs due to their appropriate mechanical, optical, and electrical properties. [7][8][9] However, a signifi cant mismatch between the Fermi levels (i.e., WFs) of PEDOT:PSS and metal oxides results in the charge carrier exchange between two materials for aligning their Fermi levels, thus forming depletion-induced Schottky barrier at the RL interface. Furthermore, sol-gel-processed metal oxides possess many charge trap sites.…”

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confidence: 99%

“…These device geometries include tandem architectures [6][7][8][9] and inverted structures. [7][8][9] Tandem PSCs are composed of two serially connected sub-cells that use low-and high-bandgap conjugated polymers with complementary absorption spectra to harvest the full solar spectrum. In contrast, inverted PSCs allow for the use of air-stable, printable metal electrodes (e.g., Ag ink) and thus exhibit much better device stability and printability than conventional PSCs that use low-work-function (WF) metal electrodes.…”

mentioning

confidence: 99%

A Depletion‐Free, Ionic, Self‐Assembled Recombination Layer for Tandem Polymer Solar Cells

Lee

Kang

Kong

et al. 2013

Advanced Energy Materials

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To increase the device effi ciency [1][2][3] and stability [3][4][5] of polymer solar cells (PSCs), intensive studies have been conducted on the development of novel device confi gurations that utilize the unique features of PSCs. These device geometries include tandem architectures [6][7][8][9] and inverted structures. [7][8][9] Tandem PSCs are composed of two serially connected sub-cells that use low-and high-bandgap conjugated polymers with complementary absorption spectra to harvest the full solar spectrum. In contrast, inverted PSCs allow for the use of air-stable, printable metal electrodes (e.g., Ag ink) and thus exhibit much better device stability and printability than conventional PSCs that use low-work-function (WF) metal electrodes. Hence, inverted tandem PSCs (I-TPSCs) that combine the advantages of both device geometries are considered to be ideal for PSCs.Despite these excellent air stability and printability of I-TPSCs, the performance of these devices has been limited by a lack of effi cient recombination layers (RLs) that electrically connect the two sub-cells. To realize an inverted tandem confi guration, a RL comprising a bilayer of p-type and n-type interfacial materials must be introduced between the front and back subcells. Currently, combinations of p-type metallic poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and n-type semiconducting metal oxides (e.g., zinc oxide (ZnO) or titanium sub-oxide (TiO x )) are widely used in RLs due to their appropriate mechanical, optical, and electrical properties. [7][8][9] However, a signifi cant mismatch between the Fermi levels (i.e., WFs) of PEDOT:PSS and metal oxides results in the charge carrier exchange between two materials for aligning their Fermi levels, thus forming depletion-induced Schottky barrier at the RL interface. Furthermore, sol-gel-processed metal oxides possess many charge trap sites. Conventional RLs require photo- [9][10][11] or chemical [ 12,13 ] doping to reduce the length of the depletion region and to fi ll the trap sites. As a result, metallic PEDOT:PSS/semiconducting metal oxide junctions may not be the best candidates for use in high-effi ciency I-TPSCs.As an alternative, the metal oxides can be replaced with polyelectrolytes (PEs). [14][15][16] By applying thin PE fi lms with thicknesses of only few nanometers, the energy level of the metallic electrodes can be modifi ed without creating unwanted energetic barriers or charge traps. This results in remarkable WF reductions in the electrodes through the formation of interfacial dipoles. [14][15][16] Here, by using ionic self-assembly of a nonconjugated polyelectrolyte (NPE) on a metallic indium tin oxide (ITO) cathode for the front cell and a PEDOT:PSS cathode for the back cell, we demonstrate an innovative method for achieving depletion-free, ionic self-assembled RLs that enable highly effi cient I-TPSC operation. Particularly, the PEDOT:PSS/ NPE RLs form tunnel junctions with different work functions of 5.1 eV and 3.9 eV on each of their surfaces. This ...

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Efficient Inverted Tandem Polymer Solar Cells with a Solution‐Processed Recombination Layer

Cited by 107 publications

References 27 publications

Effects of ultraviolet soaking on surface electronic structures of solution processed ZnO nanoparticle films in polymer solar cells

Effects of ultraviolet soaking on surface electronic structures of solution processed ZnO nanoparticle films in polymer solar cells

The Effect of Large Compositional Inhomogeneities on the Performance of Organic Solar Cells: A Numerical Study

A Depletion‐Free, Ionic, Self‐Assembled Recombination Layer for Tandem Polymer Solar Cells

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