Mathijs Adriaan Janssen

• Ma, Ke; Janssen, Mathijs Adriaan; Lian, Cheng & Van Roij, René (2022). Dynamic density functional theory for the charging of electric double layer capacitors. Journal of Chemical Physics. ISSN 0021-9606. 156(8). doi: 10.1063/5.0081827. Fulltekst i vitenarkiv
• Bisquert, Juan & Janssen, Mathijs Adriaan (2021). From Frequency Domain to Time Transient Methods for Halide Perovskite Solar Cells: The Connections of IMPS, IMVS, TPC, and TPV. The Journal of Physical Chemistry Letters. ISSN 1948-7185. 12(33), s. 7964–7971. doi: 10.1021/acs.jpclett.1c02065. Fulltekst i vitenarkiv Vis sammendrag

  The correlation of different methods of measurement can become an important tool to identify the dominant physical elements that govern the electronic and ionic dynamics in perovskite solar cells. The diverse phenomena underlying the response of halide perovskite materials to different stimuli are reflected in time-domain measurements, where transients appear with time scales spanning orders of magnitude, from nanoseconds to hours. We discuss the connection between different frequency- and time-domain methods to probe the voltage and current response of halide perovskite solar cells to different small perturbations. To solve the frequency-to-time transformation, we start from models of the transfer function of intensity-modulated photocurrent spectroscopy (IMPS) and derive the associated impulse response function, the transient photocurrent (TPC), in response to a short light pulse. Similarly, we determine the transient photovoltage (TPV) starting from the intensity-modulated photovoltage spectroscopy (IMVS) transfer function. We also discuss the open-circuit voltage decays (OCVD). We first show the response of simple equivalent circuit models, and then we treat the full model for generation–diffusion–recombination of electrons that shows a spiraling loop in IMPS. This model gives rise to overshoots in the time domain.

• Janssen, Mathijs Adriaan & Bisquert, Juan (2021). Locating the Frequency of Turnover in Thin-Film Diffusion Impedance. Journal of Physical Chemistry C. ISSN 1932-7447. 125(28), s. 15737–15741. doi: 10.1021/acs.jpcc.1c04572. Fulltekst i vitenarkiv Vis sammendrag

  The impedance of diffusion is an important tool to investigate a wide variety of systems, including electrochemical devices such as Li-ion batteries, porous electrodes, and solar cells. The classical impedance model for diffusion in a thin layer with a blocking boundary contains two separate regimes: Warburg diffusion at high frequency and capacitive charging at low frequency. Here, we provide a physical criterion for the transition between these two regimes, as the point of closest approach between early- and late-time approximations of the exact diffusion current. The resulting frequency is (π2/2)ωd with respect to the natural frequency ωd = Dn/L2, with Dn being the diffusion constant and L being the thickness of the layer.

• Sehnem, André Luiz & Janssen, Mathijs Adriaan (2021). On the time-dependent electrolyte Seebeck effect. Journal of Chemical Physics. ISSN 0021-9606. 154(16), s. 164511-1–164511-8. doi: 10.1063/5.0045137. Fulltekst i vitenarkiv Vis sammendrag

  Single-ion Soret coefficients αi characterize the tendency of ions in an electrolyte solution to move in a thermal gradient. When these coefficients differ between cations and anions, an electric field can be generated. For this so-called electrolyte Seebeck effect to occur, different thermodiffusive fluxes need to be blocked by boundaries—electrodes, for example. Local charge neutrality is then broken in the Debye- length vicinity of the electrodes. Confusingly, many authors point to these regions as the source of the thermoelectric field yet ignore them in derivations of the time-dependent Seebeck coefficient S(t), giving a false impression that the electrolyte Seebeck effect is purely a bulk phenomenon. Without enforcing local electroneutrality, we derive S(t) generated by a binary electrolyte with arbitrary ionic valencies subject to a time-dependent thermal gradient. Next, we experimentally measure S(t) for five acids, bases, and salts near titanium electrodes. For the steady state, we find S ≈ 2 mV K−1 for many electrolytes, roughly one order of magnitude larger than the predictions based on literature αi. We fit our expression for S(t) to the experimental data, treating the αi as fit parameters, and also find larger-than-literature values, accordingly.

• Janssen, Mathijs Adriaan (2021). Transmission Line Circuit and Equation for an Electrolyte-Filled Pore of Finite Length. Physical Review Letters. ISSN 0031-9007. 126(13), s. 136002-1–136002-5. doi: 10.1103/PhysRevLett.126.136002. Fulltekst i vitenarkiv Vis sammendrag

  I discuss the strong link between the transmission line (TL) equation and the TL circuit model for the charging of an electrolyte-filled pore of finite length. In particular, I show how Robin and Neumann boundary conditions to the TL equation, proposed by others on physical grounds, also emerge in the TL circuit subject to a stepwise potential. The pore relaxes with a timescale τ, an expression for which consistently follows from the TL circuit, TL equation, and from the pore’s known impedance. An approximation to τ explains the numerically determined relaxation time of the stack-electrode model of Lian et al. [Phys. Rev. Lett. 124, 076001 (2020)]

• Glatzel, Fabian; Janssen, Mathijs Adriaan & Härtel, Andreas (2021). Reversible heat production during electric double layer buildup depends sensitively on the electrolyte and its reservoir. Journal of Chemical Physics. ISSN 0021-9606. 154(6), s. 064901-1–064901-13. doi: 10.1063/5.0037218. Fulltekst i vitenarkiv
• Janssen, Mathijs Adriaan; Stenmark, Harald & Carlson, Andreas (2021). Divalent ligand-monovalent molecule binding. Soft Matter. ISSN 1744-683X. 17, s. 5375–5383 . doi: 10.1039/d1sm00070e. Fulltekst i vitenarkiv Vis sammendrag

  Simultaneous binding of a divalent ligand to two identical monovalent molecules is a widespread phenomenon in biology and chemistry. Here, we describe how two such monovalent molecules B bind to a divalent ligand AA to form the intermediate and final complexes AA·B and AA·B2. Cases wherein the total concentration [AA]T is either much larger or much smaller than the total concentration [B]T have been studied earlier, but a systematic description of comparable concentrations [AA]T and [B]T is missing. Here, we present numerical and analytical results for the concentrations [AA·B] and [AA·B2] for the entire range 0

• Breitsprecher, Konrad; Janssen, Mathijs Adriaan; Srimuk, Pattarachai; Mehdi, B. Layla; Presser, Volker & Holm, Christian [Vis alle 7 forfattere av denne artikkelen] (2020). How to speed up ion transport in nanopores. Nature Communications. ISSN 2041-1723. 11(1), s. 1–10. doi: 10.1038/s41467-020-19903-6.

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• Sehnem, André Luiz & Janssen, Mathijs Adriaan (2021). Erratum: On the time-dependent electrolyte Seebeck effect (J. Chem. Phys. (2021):(154): 164511 DOI: 10.1063/5.0045137). Journal of Chemical Physics. ISSN 0021-9606. 154(20). doi: 10.1063/5.0055838.
• Glatzel, Fabian; Janssen, Mathijs Adriaan & Härtel, Andreas (2021). Erratum: Reversible heat production during electric double layer buildup depends sensitively on the electrolyte and its reservoir (J. Chem. Phys. (2021) 154 (064901) DOI: 10.1063/5.0037218). Journal of Chemical Physics. ISSN 0021-9606. 154(13). doi: 10.1063/5.0049716.

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