Fundamentals of the nanowire solar cell: optimization of the open circuit voltage

Present day nanowire solar cells have reached an efficiency of 17.8%. Nanophotonic engineering by nanowire tapering allows for high solar light absorption. In combination with sufficiently high carrier selectivity at the contacts, the short-circuit current (Jsc) has presently reached 29.3 mA/cm2, reasonably close to the 34.6 mA/cm2 theoretical limit for InP. Although further optimization of the current is important, an equally challenging condition to approach the Shockley Queisser (S-Q) limit is to increase the open-circuit voltage (Voc) towards the radiative limit. The key requirement to reach the radiative limit is to increase the external radiative efficiency at open-circuit conditions towards unity. It is the main purpose of this review to highlight recent progress in nanophotonic engineering to further enhance the open circuit voltage of a nanowire solar cell. In addition to material optimization for increasing the internal photoluminescence efficiency, the light extraction efficiency is a major design criterion for enhancing the external radiative efficiency and thus the Voc. Since the semiconductor substrate is a sink for internally generated photoluminescence, it is equally important to eliminate the loss of emitted light into the substrate. Even at the S-Q limit, the Voc is still substantially decreased by a photon entropy loss due to the conversion of a parallel beam of photons from the sun into an isotropic emission pattern, in which each individual photon is emitted into a random direction. The 46.7% ultimate solar cell limit for direct solar irradiation can only be approached, once the cell is capable to focus all emitted photoluminescence back to the sun. We will show that nanophotonic engineering provides a pathway to approach the ultimate limit

Charge carrier-selective contacts for nanowire solar cells

Charge carrier-selective contacts transform a light-absorbing semiconductor into a photovoltaic device. Current record efficiency solar cells nearly all use advanced heterojunction contacts that simultaneously provide carrier selectivity and contact passivation. One remaining challenge with heterojunction contacts is the tradeoff between better carrier selectivity/contact passivation (thicker layers) and better carrier extraction (thinner layers). Here we demonstrate that the nanowire geometry can remove this tradeoff by utilizing a permanent local gate (molybdenum oxide surface layer) to control the carrier selectivity of an adjacent ohmic metal contact. We show an open-circuit voltage increase for single indium phosphide nanowire solar cells by up to 335 mV, ultimately reaching 835 mV, and a reduction in open-circuit voltage spread from 303 to 105 mV after application of the surface gate. Importantly, reference experiments show that the carriers are not extracted via the molybdenum oxide but the ohmic metal contacts at the wire ends.QN/Bakkers La

Josephson radiation and shot noise of a semiconductor nanowire junction [version 1]

Raw data and code that belong to the paper "Josephson radiation and shot noise of a semiconductor nanowire junction". For usage instructions, see README.txt

Scripts accompanying the publication "Conductance through a helical state in an indium antimonide nanowire"

Scripts accompanying the publication "Conductance through a helical state in an indium antimonide nanowire" - published in Nature Communcations. The scripts are written in python (.py) and jupyter notebook (.ipynb

Crossed Andreev Reflection in InSb flake Josephson Junctions

Data collection and code examples for plotting the figures of the manuscript entitled: Crossed Andreev Reflection in InSb Flake Josephson Junctions

Data and scripts accompanying the publication "Conductance through a helical state in an indium antimonide nanowire"

Data and scripts accompanying the publication "Conductance through a helical state in an indium antimonide nanowire" - published in Nature Communcations

Data and code: Supercurrent interference in few-mode nanowire Josephson junctions

Data and code for the paper: "Supercurrent interference in few-mode nanowire Josephson junctions" by Vincent Mourik, Daniel B. Szombati, Bas Nijholt, David J. van Woerkom, Attila Geresdi, Jun Chen, Viacheslav P. Ostroukh, Anton R. Akhmerov, Sebastian R. Plissard, Diana Car, Erik P. A. M. Bakkers, Dmitry I. Pikulin, Leo P. Kouwenhoven, and Sergey M. Frolov

Dataset underlying the paper: Parity transitions in the superconducting ground state of hybrid InSb-Al Coulomb islands

Data for the figures in the paper 'Parity transitions in the superconducting ground state of hybrid InSb-Al Coulomb islands