Photoactive area modification in bulk heterojunction organic solar cells using optimization of electrochemically synthesized ZnO nanorods

Abstract

In this work, ZnO nanorod arrays grown by an electrochemical deposition method are investigated. The crucial parameters of length, diameter, and density of the nanorods are optimized over the synthesize process and nanorods growth time. Crystalline structure, morphologies, and optical properties of ZnO nanorod arrays are studied by different techniques such as x-ray diffraction, scanning electron microscope, atomic force microscope, and UV–visible transmission spectra. The ZnO nanorod arrays are employed in an inverted bulk heterojunction organic solar cell of Poly (3-hexylthiophene):[6-6] Phenyl-(6) butyric acid methyl ester to introduce more surface contact between the electron transporter layer and the active layer. Our results show that the deposition time is a very important factor to achieve the aligned and uniform ZnO nanorods with suitable surface density which is required for effective infiltration of active area into the ZnO nanorod spacing and make a maximum interfacial surface contact for electron collection, as overgrowing causes nanorods to be too dense and thick and results in high resistance and lower visible light transmittance. By optimizing the thickness of the active layer on top of ZnO nanorods, an improved efficiency of 3.17% with a high FF beyond 60% was achieved.

Inverted organic solar cells with solvothermal synthesized vanadium-doped TiO 2 thin films as efficient electron transport layer

“…Afterward for electron transport layer deposition, 10% and 40% stable solutions of pure and vanadium-doped TiO 2 NPs were dissolved in 2-methoxy ethanol to be deposited using doctor blade method (4 samples with the thicknesses of 30 and 60 nm, respectively). [12] In the next step, 100 µL of the mentioned solutions was injected into the substrate. Finally, deposition started with a speed of 40 mm/s on the heated substrate (65 • C).…”

“…[3,9] In this structure, a buffer layer is inserted between the active layers and electrodes. Different n-type metal oxides such as ZnO [9][10][11][12] and TiO 2 , [13][14][15] alkali metal oxides like LiF [16] and Cs 2 CO 3 , [17,18] and in some cases ultra thin layers of Ca [19,20] are used as the electron-selective and holeblocking layer in PSCs.…”