Effect of CuI Anode Buffer Layer on the Growth of Polymers Thin Films and on the Performances of Organic Solar Cells

Abstract

Organic photovoltaic cells using polymer belonging to the aniline-heteroaryl family as electron donor have been achieved by thermal evaporation. We show that the properties of the polymer film, morphology, molecule order and conductivity depend strongly on the bottom anode buffer layer. While cells without anode buffer layer or with MoO 3 or CuI anode buffer layer have been probed, we show that CuI allows improving strongly the cells efficiency through an improvement of the morphology and conductivity of the polymer film. This shows that although it is necessary a good band matching at the interface, this is not sufficient, because the templating effect of CuI on the polymer film is primordial for photovoltaic cells improvement.

Synthesis of Random Copolymers of 2,6-Di(thiophen-2-Yl)aniline and 2,2'-(Thiophen-2,5-Diyl)dianiline With Aniline and Its Evaluation in Organic Solar Cells

“…This means the polymer growth occurs just through aniline unit(s) of the monomers, corroborating thus the results of a previous work [13]. On the other hand, in both cases the appearance of weak signals at about 7.50 ppm, ascribed to PANI chain benzenoid and quinoid aromatic protons, were observed [14,[19][20]. At 4.00 ppm, where the signal associated to amino groups shows up, a second band, downfield shifted, starts emerging.…”

“…hybrid precursors, was set forth. This fact was successfully corroborated in such investigations [13][14].…”

“…This signal is also observed in the coPANIB spectrum, but now appears superimposed with the signal assigned to π-π* transitions of the thiophene ring. coPANIB also displayed a broad band reaching over the 800 nm, that would reflect the electronic population associated to quinoid structures [14].…”

“…The obtained wavelength divides the constant 1242 (Eg = hc/l), giving an estimate bandgap value in eV [13][14]28]. According to the data shown in Fig.…”

Highly efficient organic solar cells based on a robust room-temperature solution-processed copper iodide hole transporter

“…CuI was successfully introduced in the past into dye-sensitzed solar cells (DSSCs) by Tennakone and coworkers, [22] in which p-type CuI was used as hole conducting layer [21][22][23][24][25][26][27]. Vacuum-deposited CuI has also been used to template the stacking orientation of vacuum-deposited small-molecule thin films such as Zinc phthalocyanine (ZnPc) [28,29] and Copper phthalocyanine (CuPc), [30] as well as polymers such as poly(3-hexylthiophene) (P3HT) [31,32] and poly(4-(2-thiophenaniline)) (P42TA) in OPV applications [33]. Here, we characterize in detail solutionprocessed CuI thin films in terms of their microstructure, optical and electronic properties.…”