Licf3so3

Triethylene glycol dimethyl ether (triglyme, 99%) and molecular sieves
(pore size of 3 Å, diameter of 1–2 mm) were purchased
from Alfa Aesar. Ethylene carbonate (EC, 98%) and dimethyl carbonate
(DMC, 98%) were purchased from Sigma-Aldrich. In order to remove the
residual moisture, molecular sieves were first activated by heating
to 180 °C under vacuum overnight and then added to the solvents.
LiTf (LiCF₃SO₃, 98%, Sigma-Aldrich) and NaTf
(NaCF₃SO₃, 99.5%, Solvionic) salts were dried
prior to use (at 120 °C under vacuum, overnight). The moisture
in the electrolytes was controlled to be under 20 ppm, as confirmed
by Karl Fischer titration performed in an Ar-filled glovebox (atmosphere:
O₂ < 0.1 ppm, H₂O < 0.1 ppm).
Due
to the high reactivity of lithium and sodium metals, surface degradation
is expected even in an Ar-filled glovebox. Thus, alkali metals used
(Li rod with 99.9% trace metal basis and Na cubes containing mineral
oil with 99.9% trace metals basis, both purchased from Sigma-Aldrich)
were cut freshly each time right before the electrodes were prepared.
Li and Na were subsequently sandwiched between two Celgard separators,
roll-pressed to approximately the same thickness (0.15 mm), and then
cut into disks with a diameter of 10 mm.

PEO (M.W. 6 × 10⁶), lithium trifluoromethanesulfonate (LiCF₃SO₃) and halloysite nanotube (HNTs; Al₂Si₂O₅(OH)₄.2H₂O) were purchased from Sigma-Aldrich. Tetrahydrofuran (THF) was purchased from RCI Labscan.

The chemical structure of the host materials poly(9-vinycarbazole) (PVK, Sigma-Aldrich) and 1,3-bis[2-(4-tert-butylphenyl)-1,3,4-oxadiazo-5-yl]benzene (OXD-7, Lumtec) are presented in the inset of Fig. 2a, b. Other investigated host compounds include the commercially available materials Triplet Host 123 (TH123, Merck) and Triplet Host 105 (TH105, Merck). A wide range of commercially available guest compounds were investigated, including tris[2-(5-substituent-phenyl)-pyridinato]iridium(III) (Ir(R-ppy)₃, Merck, see Fig. 2d), tris[2-(p-tolyl)pyridine]iridium(III) (Ir(mppy)₃, Lumtec), and tris[2-(4-n-hexylphenyl)quinoline]iridium(III) (Hex-Ir(piq)₃, Lumtec); see insets in Supplementary Fig. 4a and b. The investigated electrolytes are tetrahexylammonium tetrafluoroborate (THABF₄, Sigma-Aldrich, see Fig. 2e) and LiCF₃SO₃ (Sigma-Aldrich) dissolved in hydroxyl-capped trimethylolpropane ethoxylate (TMPE-OH, M_w = 450 g mol⁻¹, Sigma-Aldrich). All of the materials were used as received. The master solutions were prepared by dissolving the constituent material in chlorobenzene at a concentration of 15 mg ml⁻¹ (PVK), 30 mg ml⁻¹ (OXD-7), 20 mg ml⁻¹ (PVK:OXD-7), 20 mg ml⁻¹ (TH123:TH105), 10 mg ml⁻¹ (THABF₄), and 10 mg ml⁻¹ (TMPE-OH:LiCF₃SO₃). The master solutions were stirred on a magnetic hot plate at 343 K for at least 5 h before further processing.

P3HT was purchased from Zhejiang Optical & Electronic Technology Co. Ltd. PEO (MW = 100000) and lithium trifluoromethanesulfonate (LiCF₃SO₃) were purchased from Sigma-Aldrich Co. Ltd. These substances were used as received. The Pt/P3HT/PEO + Li⁺/Pt device was fabricated using following methodology. First, a 100 nm Pt film was deposited on a Si substrate and was used as the bottom electrode (BE). Second, a 3-µL dichlorobenzene solution of P3HT was spin-coated on the BE and heated inside a glove box filled with N₂. The dichlorobenzene solution of P3HT was spin-coated onto the BE at 500, 3000, and 1500 rpm for 10, 30, and 20 s, respectively. The P3HT film was baked at 100°C for 1 h, and then at 140°C for 20 min; its thickness was about 25 nm. Third, a 3-µL aqueous solution of the PEO and LiCF₃SO₃ was drop cast on the P3HT film and baked at 60°C for 20 min. Finally, the Pt top electrodes (TEs) with a thickness of 80 nm and a diameter of 300 µm were deposited on the PEO + Li⁺ layer with electron beam deposition using a shadow mask. A schematic of device structure is shown in Figure 1a.