Plasmon-Mediated Absorption and Photocurrent Spectra in Sensitized Solar Cells

Abstract

Plasmon resonances in metal nanoparticles (MNPs) can be used to enhance the efficiency of photoinduced electron transfer from a sensitizer (a molecule or a quantum dot (QD)) to a semiconductor electrode. Here we use a model Hamiltonian approach to study the optical response and the steady state electron injection rate (SSIR) of a hybrid system, consisting of a sensitizer that is coupled to a metal nanoparticle via dipole coupling and to a semiconductor electrode via electronic coupling. Counterintuitively, the total absorption cross section for the coupled system and the SSIR are correlated only for small coupling; in the relevant domain of large enhancement we observe anticorrelation. A maximum SSIR as a function of the dipole coupling strength is predicted analytically, and shown to result from the competition between the plasmonic field enhancement and the Purcell effect. In the case of pulsed excitation, the appearance of a Fano resonance and its reversal is illustrated as the dipole coupling strength grows, and for strong couplings Rabi splitting is observed. Interestingly, in the case of continuous wave (CW) excitation, we find plasmon-induced resonance energy transfer, leading to strong SSIR at incident light frequencies that are far detuned from the sensitizer transition frequency and are fully controllable.

Elucidating the Contributions of Plasmon-Induced Excitons and Hot Carriers to the Photocurrent of Molecular Junctions

“…As all these mechanisms could be simultaneously active in any given system, theoretical effort to elucidate their relative contributions has already been initiated, ,,− suggesting, for example, larger contribution of the PIRET if an overlap between the plasmon and the molecule (or semiconductor) absorption spectra exists and the decay of the plasmons is sufficiently slow to maintain its collective behavior. PIRET in this case is suggested to be revealed as asymmetry in the optical response of a system near the plasmon peak as a result of interference effects .…”

Measuring nanoparticle-induced resonance energy transfer effect by electrogenerated chemiluminescent reactions

“…4,[19][20][21] In point of fact, the enhancement of photoluminescence (PL) by a nanoparticle uses in an effective way the coupling between excited dyes and the localized surface plasmon resonance (SPR) in metal nanostructures in an effective way. This interaction effect has contributed to the development of nanotechnology: [22][23][24][25][26][27] for instance, solar energy storage and conversion [22][23][24] and optical biosensing, [25][26][27] rely on this type of the energy transfer.…”

Origin of Plasmon Lineshape and Enhanced Hot Electron Generation in Metal Nanoparticles

“…Plasmons are collective oscillations of the conduction electrons in a MNP. , Due to their ability to focus and enhance electromagnetic fields, surface plasmons have inviting photovoltaic − and photocatalytic − applications. It has been shown that in small MNPs the plasmon decays mainly through the excitation of electron–hole pairs (Landau damping) − that results in the generation of hot electrons (hot as they have high temperature relative to their environment).…”

“…Note that, although the global coherence is gradually lost, the coupling still exists, and the coherence in each subsystem is maintained. The relevant dephasing and relaxation process is described using the Lindblad formalism, ,, with the superoperator L given through where f FD denotes the Fermi–Dirac distribution, with ϵ, μ, and T being the energy, chemical potential, and temperature, respectively. The diagonal part describes the electron–electron thermalization and the electron–phonon relaxation, with corresponding rates γ e–e and γ e–p .…”

“…Note that, although the global coherence is gradually lost, the coupling still exists, and the coherence in each subsystem is maintained. The relevant dephasing and relaxation process is described using the Lindblad formalism, 6,7,34 with the superoperator L given through…”