Enhancing the Tunability of the Open-Circuit Voltage of Hybrid Photovoltaics with Mixed Molecular Monolayers

Barnea-Nehoshtan, Lee; Nayak, Pabitra K.; Shu, Andrew; Bendikov, Tatyana; Kahn, Antoine

doi:10.1021/am4056134

Cited by 6 publications

(8 citation statements)

References 47 publications

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“…The integration of a buffer layer at the interface of a MoS 2 /PbS photodetector has shown to strongly impact the electrical tunability due to controlled doping and defect passivation . Apart from ALD-deposited thin films employed in this study, the exploitation of molecular self-assembled monolayers at the interface may also lead to efficient cross-linking between QDs and TMDCs and simultaneously passivate electronic defect states at the TMDC surface as demonstrated for other materials in solar cell devices. − …”

Section: Future Outlook On Sensitized Photo-fetsmentioning

confidence: 95%

Photo-FETs: Phototransistors Enabled by 2D and 0D Nanomaterials

2016

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The large diversity of applications in our daily lives that rely on photodetection Photodetectors are one of the key components in many optoelectronic devices which transduce optical into electrical information. Today, photodetectors have reached a mature technology level and address a huge application spectrum including imaging, remote sensing, fibre-optic communication and spectroscopy among many others. However, to tackle challenges and to surpass existing limitations in sensitivity of state-of-the-art photodetector systems, new device architectures and material systems are needed which offer low-cost fabrication and high performance over a wide spectral range. The active research field on photodetection grows and many novel nanostructured material systems 1 have been employed for light sensing including Quantum dots 2,3 , Perovskites 4,5 , organic molecules and polymers 6,7 , Carbon Nanotubes 8,9 , Graphene 10,11 and the large field of semiconducting 2D materials such as the transition metal dichalcogenides (TMDCs) and black phosphorus 12,13 .Photodetector performance is governed by both the optical and electronic properties of the employed semiconductor. The former determines the spectral coverage and quantum efficiency of the detector whereas the latter determines, through the carrier transport and carrier density, the amount of dark current flowing through the device, as well as the efficiency of charge separation and collection upon illumination. The key parameters for a strong signal response are a high photon to electron conversion rate (quantum efficiency) and ideally an inherent gain 3 mechanism, which yields multiple carriers per absorbed photon. The response signal is then weighed against the noise portion of the ratio, which has to be minimized for maximum sensitivity. There are several device-external noise sources, such as the photon noise due to the statistical arrival of photons on the device or the read-out noise in photodetector arrays that originates in preamplifier electronics. Here, we will put emphasis on the device (photodetector pixel) inherent noise, which stems partially from thermally generated charge carriers and also from the intrinsic carrier density that contribute to the dark current of the device (shot noise limit) as well as flicker noise (1/f). It is however important to note that the sensitivity of a detector with inherent noise lower than the noise floor of commercially used CMOS read-out circuits, typically met in photodiodes, is limited by the latter, thus a photodetector technology with an inherent gain mechanism is desired to alleviate this effect.The relevant performance metrics and terminology used throughout this article are described in Box 1. Box 1 -Performance metrics for photodetection Responsivity [A/W]The fundamental process behind photodetection is absorption of light. Responsivity R, a measure of output current per incoming optical power in units of A/W, describes how a detector system responds to illumination. Responsivity depends on the incident...

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Section: Future Outlook On Sensitized Photo-fetsmentioning

confidence: 95%

Photo-FETs: Phototransistors Enabled by 2D and 0D Nanomaterials

2016

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“…However, ref shows that flexible molecules can rearrange to minimize the Coulombic repulsion and this possibility should be considered in designing new molecular systems. An amine group at the terminal of an alkyl chain can also serve to reduce the work function, while a fluoride, , or other halides, , increase it. The effect of systematic increase of the degree of fluorination on the work-function was extensively studied. ,,, Increasing the number of per-fluorinated methylene (CF 2 ) groups affects a variety of properties like bulkiness and polarizability but is not expected to affect the dipole directly: although each C–F bond is strongly polarized, the dipoles of neighboring CF 2 units cancel each other.…”

Section: Molecular Dipoles As a 2d Dipolar Arraymentioning

confidence: 99%

“…We now move from a surface dipole to an interface dipole, such as results from inserting a molecular monolayer into a metal/semiconductor (“Schottky”) junction (see Figure D for an illustration). Molecular-dipolar modification of a Schottky barrier was demonstrated on numerous metal/semiconductor junctions, made with different semiconductors (Si, ,, oxidized Si, GaAs, , SiC, TiO 2 , ITO, , and ZnO , ) and using different types of monolayers and top contacts. This vast evidence is represented here by two examples in Figure .…”

Section: Molecular Dipoles As a 2d Dipolar Arraymentioning

confidence: 99%

Chemical Modification of Semiconductor Surfaces for Molecular Electronics

2017

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Inserting molecular monolayers within metal/semiconductor interfaces provides one of the most powerful expressions of how minute chemical modifications can affect electronic devices. This topic also has direct importance for technology as it can help improve the efficiency of a variety of electronic devices such as solar cells, LEDs, sensors, and possible future bioelectronic ones. The review covers the main aspects of using chemistry to control the various aspects of interface electrostatics, such as passivation of interface states and alignment of energy levels by intrinsic molecular polarization, as well as charge rearrangement with the adjacent metal and semiconducting contacts. One of the greatest merits of molecular monolayers is their capability to form excellent thin dielectrics, yielding rich and unique current-voltage characteristics for transport across metal/molecular monolayer/semiconductor interfaces. We explain the interplay between the monolayer as tunneling barrier on the one hand, and the electrostatic barrier within the semiconductor, due to its space-charge region, on the other hand, as well as how different monolayer chemistries control each of these barriers. Practical tools to experimentally identify these two barriers and distinguish between them are given, followed by a short look to the future. This review is accompanied by another one, concerning the formation of large-area molecular junctions and charge transport that is dominated solely by molecules.

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“…27 Molecules, unlike inorganic wide bandgap semiconductors, possess a plurality of structural parameters that can be tuned in these systems: the length of the molecule, the conjugated or aliphatic character and the end-functional groups that serve to strongly bind on a given surface and passivate electronic defect states. [27][28][29][30][31][32][33][34][35] Not to exclude also their solution processability which is a significantly lower cost manufacturing process compared to atomic layer deposition.…”

Section: Introductionmentioning

confidence: 99%