Energy-Level Engineering at ZnO/Oligophenylene Interfaces with Phosphonate-Based Self-Assembled Monolayers

Timpel, Melanie; Nardi, Marco Vittorio; Ligorio, Giovanni; Wegner, Berthold; Pätzel, Michael; Kobin, Björn; Hecht, Stefan; Koch, Norbert

doi:10.1021/acsami.5b01669

Cited by 32 publications

(35 citation statements)

References 29 publications

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“…If so, the addition of a molecular dipole layer at the organicinorganic interface might be used to produce a more staggered ELA between the organic and silicon materials, making exciton dissociation more favourable. 79 Thin inorganic interlayers might also be implemented to achieve the same result. New SF chromophores with a slightly higher triplet energy compared to Tc, or a smaller ionisation potential, may also be interesting in this respect.…”

Section: Overcoming Hindered Exciton Harvestingmentioning

confidence: 99%

Crystalline silicon solar cells with tetracene interlayers: the path to silicon-singlet fission heterojunction devices

et al. 2018

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Singlet exciton fission is an exciton multiplication process that occurs in certain organic materials, converting the energy of single highly-energetic photons into pairs of triplet excitons. This could be used to boost the conversion efficiency of crystalline silicon solar cells by creating photocurrent from energy that is usually lost to thermalisation. An appealing method of implementing singlet fission with crystalline silicon is to incorporate singlet fission media directly into a crystalline silicon device. To this end, we developed a solar cell that pairs the electron-selective contact of a high-efficiency silicon heterojunction cell with an organic singlet fission material, tetracene, and a PEDOT:PSS hole extraction layer. Tetracene and n-type crystalline silicon meet in a direct organic-inorganic heterojunction. In this concept the tetracene layer selectively absorbs blue-green light, generating triplet pairs that can dissociate or resonantly transfer at the organo-silicon interface, while lower-energy light is transmitted to the silicon absorber. UV photoemission measurements of the organicinorganic interface showed an energy level alignment conducive to selective hole extraction from silicon by the organic layer. This was borne out by current-voltage measurements of devices subsequently produced. In these devices, the silicon substrate remained well-passivated beneath the tetracene thin film. Light absorption in the tetracene layer created a net reduction in current for the solar cell, but optical modelling of the external quantum efficiency spectrum suggested a small photocurrent contribution from the layer. This is a promising first result for the direct heterojunction approach to singlet fission on crystalline silicon.

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Section: Overcoming Hindered Exciton Harvestingmentioning

confidence: 99%

Crystalline silicon solar cells with tetracene interlayers: the path to silicon-singlet fission heterojunction devices

et al. 2018

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“…[1][2][3] These properties together with a type-I level alignment at the hybrid interface would be ideally suited for light-emitting applications. [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] The adsorption of a molecular layer on inorganic surfaces has also been exploited to tune the work function of the inorganic component. [6][7][8][9][10] Prerequisite for that is the lightinduced creation of hybrid or charge-transfer excitons, which exhibit the hole to a large extent on one side of the interface while the excited electron would reside on the other side.…”

Section: Introductionmentioning

confidence: 99%

Electronic and Optical Excitations at the Pyridine/ZnO(101¯0) Hybrid Interface

Turkina

Nabok

Guļāns

et al. 2018

Advcd Theory and Sims

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By combining all-electron density-functional theory with many-body perturbation theory, a prototypical inorganic/organic hybrid system, composed of pyridine molecules that are chemisorbed on the nonpolar ZnO(1010) surface is investigated. The G 0 W 0 approximation is employed to describe its one-particle excitations in terms of the quasiparticle band structure, and the Bethe-Salpeter equation is solved to obtain the absorption spectrum. The different character of the constituents leads to very diverse self-energy corrections of individual Kohn-Sham states, and thus the G 0 W 0 band structure is distinctively different from its DFT counterpart, that is, many-body effects cannot be regarded as a rigid shift of the conduction bands. The nature of the optical excitations at the interface over a wide energy range is explored and it is shown that various kinds of electron-hole pairs are formed, comprising hybrid excitons and (hybrid) charge-transfer excitations. The absorption onset is characterized by a strongly bound brightZnO-dominated hybrid exciton. For the selected examples of either exciton type, the individual contributions from the valence and conduction bands are analyzed and the binding strength and extension of the electron-hole wavefunctions are discussed.

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“…The higher mobility for P‐TPA processed device implies hole carrier transport is drastically enhanced in the help of crosslinkable polymer P‐TPA HTL, and thus a very high J sc is expected for the CdTe NC Device D with P‐TPA. Based on the C–V , TPV and SCLC results, we speculate that a dipole layer is formed when the P‐TPA layer is incorporated at the CdTe/Au interface . As presented in Figure d, the formation of the dipole layer connecting the CdTe active layer and contact electrode causes a vacuum energy level shift and thus facilitates hole extraction due to the reduced hole injection barrier.…”

Section: Resultsmentioning

confidence: 87%

Interface Engineering for Both Cathode and Anode Enables Low‐Cost Highly Efficient Solution‐Processed CdTe Nanocrystal Solar Cells

Rong

Guo

Lian

et al. 2019

Adv Funct Materials

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Low‐cost solution‐processed CdTe nanocrystal (NC) solar cells always suffer from a high interface energy barrier and unbalanced hole/electron transport as well as anisotropic atom diffusion on the CdTe surface due to the limited amount of hole/electron interface materials or the difficulty in interface processing. In this work, a novel strategy is first adopted with gradient electron transport layer (CdS/CdSe) modification in the cathode and a new crosslinkable hole transport polymer (P‐TPA) implantation in the anode. The carrier recombination at interfaces is greatly decreased and thus the carrier collection is increased. Moreover, the light harvesting is improved both in short and long wavelength regions, making Jsc and Voc increase simultaneously. A champion solar cell shows a very high power conversion efficiency of 9.2% and an outstanding Jsc of 25.31 mA cm−2, which are among the highest values for all solution‐processed CdTe NC solar cells with a superstrate structure, and the latter value is even higher than that of traditional thick CdTe thin‐film solar cells (2 µm) via the high temperature close space sublimation method. This work demonstrates that facile surface modifications in both the cathode and anode with stepped extraction and organic–inorganic hybridization are very promising in constructing next‐generation highly efficient NC photovoltaic devices.

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Energy-Level Engineering at ZnO/Oligophenylene Interfaces with Phosphonate-Based Self-Assembled Monolayers

Cited by 32 publications

References 29 publications

Crystalline silicon solar cells with tetracene interlayers: the path to silicon-singlet fission heterojunction devices

Crystalline silicon solar cells with tetracene interlayers: the path to silicon-singlet fission heterojunction devices

Electronic and Optical Excitations at the Pyridine/ZnO(101¯0) Hybrid Interface

Interface Engineering for Both Cathode and Anode Enables Low‐Cost Highly Efficient Solution‐Processed CdTe Nanocrystal Solar Cells

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