Singlet Fission for Photovoltaics with 130 % Injection Efficiency

Abstract

A novel pentacene dimer (P2) and a structurally analogous monomer (P1) were synthesized for use in n-type dye-sensitized solar cells. In P2, the triplet excited states formed by the rapid, spin-allowed process singlet fission were expected to enable carrier multiplication in comparison to the slow, spin-forbidden intersystem crossing seen in P1. A meta-positioning of the two pentacenes and the carboxylate anchor were chosen in P2 to balance the intramolecular dynamics of singlet fission and electron injection. Electron injection from energetically low-lying triplet excited states of pentacene units necessitated the intrinsic and extrinsic lowering of the Fermi level of the semiconductor. Indium-zinc oxide in the presence of Li was found to be the optimum choice for the photoelectrodes. Efficient electron injection from the triplet excited states of P1 and P2 was found, with a carrier multiplication of nearly 130 %.

Tuning Intramolecular Förster Resonance Energy Transfer and Activating Intramolecular Singlet Fission

“…[14] SubPc-Pnc 2 s 4-6 were prepared by an axial substitution reaction starting with the corresponding chloro-precursors via the generation of aSubPc-triflate intermediate,following aprocedure reported by us (Figure 1a nd Supporting Information). [16] Steady-state spectroscopy was used to screen the groundand excited-state interactions between SubPcs and Pnc 2 .T he absorption spectra of the three SubPc reference compounds, namely 1, 2,and 3,intoluene show aB/Soret-band at around 320 nm as well as aQ -band at 565, 572, and 601 nm, respectively (Figures S18 a-c). [16] Steady-state spectroscopy was used to screen the groundand excited-state interactions between SubPcs and Pnc 2 .T he absorption spectra of the three SubPc reference compounds, namely 1, 2,and 3,intoluene show aB/Soret-band at around 320 nm as well as aQ -band at 565, 572, and 601 nm, respectively (Figures S18 a-c).…”

“…[24] In conclusion, we have designed, synthesized, and characterized three novel SubPc-Pnc 2 conjugates to activate as equence of intramolecular FRET and SF.T ot his end, a meta-phenylene tethered Pnc 2 was linked through acarboxylate group to different SubPcs,p robed by means of fsTA/ nsTA, and analyzed by multiwavelength and global analyses. [16] Linking the two concepts enables abroader incident photonto-current conversion efficiency. [16] Linking the two concepts enables abroader incident photonto-current conversion efficiency.…”

Feinabstimmung von intramolekularem resonantem Förster‐Energietransfer und Aktivierung intramolekularer Singulettspaltung

“…Diesbezüglich erwähnenswert ist eine kürzlich erschienene Machbarkeitsstudie in Hinblick auf die Integration eines meta-Phenylen-verbrückten Pnc 2 in eine Farbstoffsolarzelle und den Nachweis von 130 %I njektionseffizienz. [16] Eine Verknüpfung der beiden Konzepte führt zwangsläufig zu einer breiteren inzidenten Photon-zu-Strom-Umwandlungseffizienz.…”

“…[14] SubPc-Pnc 2 s 4-6 wurden mithilfe einer axialen Substitutionsreaktion hergestellt. [16] Stationäre Spektroskopie wurde verwendet, um die Konjugate auf Wechselwirkungen zwischen den SubPcs und dem Pnc 2 im Grundzustand sowie im angeregten Zustand hin zu untersuchen. [15] Pnc 2 7 wurde gemäß einer kürzlich beschriebenen Prozedur hergestellt.…”

“…[15] Pnc 2 7 wurde gemäß einer kürzlich beschriebenen Prozedur hergestellt. [16] Stationäre Spektroskopie wurde verwendet, um die Konjugate auf Wechselwirkungen zwischen den SubPcs und dem Pnc 2 im Grundzustand sowie im angeregten Zustand hin zu untersuchen. Die Absorptionsspektren der drei SubPc-Referenzverbindungen, sprich 1, 2 und 3,z eigen in Toluol eine B-/Soret-Bande bei etwa 320 nm und eine Q-Bande bei 565, 572 bzw.6 01 nm (Abbildung S18 a-c der SI).…”