Among gas sensing materials, molecular materials are extensively studied because they offer lots of possibilities to tune their electrical and optical properties and the intermolecular interactions they can develop with the target species. Among molecular materials, porphyrinoids, namely phthalocyanines and porphyrins have been highly studied [
1,
2,
3,
4]. They are characterized by large π-aromatic systems and can reversibly interact with many molecules, by H-bonds, dipole-dipole and van der Waals interactions, their metal center offering coordination bonding. They offer the possibility of electron transfer with redox active species. This is the reason why they have been used in numerous applications, e.g. for air quality monitoring [
5], for controlling the freshness of food [
6,
7] and also for the analysis of biomarkers in breath [
8]. Another family of porphyrinoids has been introduced more recently in the field of chemosensors, namely corroles [
9,
10,
11,
12], which have been used as sensing materials associated with optical, acoustic, electrochemical and conductometric transducers, as recently reviewed [
13]. While porphyrins are characterized by an aromatic macrocyclic system containing 22 electrons, corroles are contracted porphyrins, with a molecular skeleton featuring that of corrin, the nucleus of Vitamin B12. Corrole was reported for the first time in the early 60s [
14], but it gained renewed attention recently, after the discovery of simple synthetic routes for its preparation [
15,
16]. Considering conductometric sensors, because of the rather low conductivity of corroles, they are often associated with more conducting materials, e.g. carbon nanotubes [
10] and reduced graphene oxide [
17], both applied to the detection of nitrogen dioxide. Another way to use low conducting material in conductometric transducers is to incorporate them into heterojunctions. Thus, two types of molecular material – based heterojunction devices were recently reported, namely double layer heterojunctions [
18] and double lateral heterojunctions [
19]. The latter were obtained by depositing material by an electrodeposition technique, as electropolymerization. Thus, starting from 2,3,5,6-tetrafluoroaniline, we deposited the perfluoropolyaniline [
19] and from the zinc porphine we deposited the corresponding polyporphine [
20]. Very recently, we reported the first example of electrodeposited polycorrole, starting from 5,10,15-(4-aminophenyl)corrolato]copper(III) as monomer [
21]. In the case of double layer heterojunctions, the deposition technique can be the evaporation under vacuum [
22,
23]. or any solution processing technique [
24]. The common point of these heterojunction devices is that the top layer is made of a more conducting material (
Figure 1).
In the present work, we report the use of Cu (III)-tris(pentafluorophenyl) corrole (CuTpFPC,
1) and Cu (III)-tris(p-methoxyphenyl) corrole (Cu-(pmethoxy) TPC,
2) as sublayers in molecular materials – based double layer heterojunction devices (
Figure 1a), combining them with a highly conducting molecular material, namely the lutetium bisphthalocyanine, LuPc
2. Due to its radical nature, LuPc
2 exhibits a high conductivity at room temperature and can be easily oxidized and reduced [
25], which make such a sensor highly sensitive to redox active species [
2]. However, the transport properties of these heterojunction devices are determined by the nature of charge carriers in the sublayer, which can be p-type, n-type or ambipolar [
26].