Photomemristive sensing via charge storage in 2D carbon nitrides

Abstract

We present a photomemristive sensing concept based on light-induced charge storage in the 2D carbon nitride K-PHI. Our design enables memory sensing with tuneable dynamic concentration ranges, combined with diverse operation and readout modes.

Influence of Ion Exchange on Photoresponsive Properties of Potassium Poly(heptazine imide)

“…A new absorption band due to photochromism emerged at approximately 670 nm, which is common to all samples. The change in the absorption band of K δ H 3−δ PHI due to photochromism is consistent with that of the solution sample of KPHI. ,− K δ H 3−δ PHI is classified as a thermally reversible T-type photochromic substance because it shows a reversible color change that gradually returns to yellow at room temperature in all samples . The fact that the same absorption bands appear by photochromism suggests that the excited state in which the sample exhibits a blue color may be approximately independent of δ.…”

An integrated solar battery based on a charge storing 2D carbon nitride

“…1(b)): Films of K-PHI on indium tin oxide substrates (ITO) were prepared according to a procedure recently described by us. 17,29 In brief, K-PHI was synthesized in a salt melt containing KSCN and the 1D heptazine based polymer melon. 35,44,45 Subsequently, the product was washed, exfoliated via sonication in isopropanol, and homogeneous films of 0.5-2 mm thickness were obtained via dip coating (see Methods section and ESI, † Section S1 for more details).…”

“…We recently reported a bifunctional solar battery electrode material based on the fully earth-abundant 2D carbon nitride potassium poly(heptazine imide) (K-PHI). 17 Upon light excitation (bandgap of B2.7 eV), electron-hole pair separation, and extraction of the hole, K-PHI can ''trap'' photoexcited electrons up to several hours 28,29 to days 30,31 and release them on demand, accompanied by a color change from yellow to blue. This combination of optoelectronic and optoionic properties, which are linked to photointercalation of K + ions 32 and electron trapping in an intercalation band within the bandgap produces (pseudo)capacitive electron storage 17,29 and has led to applications in ''dark'' photocatalysis, [33][34][35][36][37] photomemristive sensing, 29 and multifunctional light-driven microswimmers.…”

“…17 Upon light excitation (bandgap of B2.7 eV), electron-hole pair separation, and extraction of the hole, K-PHI can ''trap'' photoexcited electrons up to several hours 28,29 to days 30,31 and release them on demand, accompanied by a color change from yellow to blue. This combination of optoelectronic and optoionic properties, which are linked to photointercalation of K + ions 32 and electron trapping in an intercalation band within the bandgap produces (pseudo)capacitive electron storage 17,29 and has led to applications in ''dark'' photocatalysis, [33][34][35][36][37] photomemristive sensing, 29 and multifunctional light-driven microswimmers. 38,39 Herein, we design a proof-of-concept ''direct solar battery'' using K-PHI as active layer, which is tasked with absorbing light and storing photoexcited electrons as well as balancing charges with intrinsic K + ion movement.…”

Formable Optoelectronic Functional Composites with Potassium Poly(heptazine imide)

“…The change in the absorption band of K-PHI due to photochromism was also consistent with that of the K-PHI solution. 2,5,8,9 The previous study has reported that isolated crystallites of K-PHI tend to aggregate upon freeze-drying. The optical gap of such solid K-PHI was found to increase substantially over the original K-PHI due to a decrease in the conjugation length of the PHI framework and partial detachment.…”