Optimization and Development of ITO-Free Plasmonic Gold Nanoparticles Assisted Inverted Organic Solar Cells

This paper focuses on the fabrication of an ITO-free plasmonic assisted inverted organic solar cell (OSC) constituting aluminium doped zinc oxide (AZO) as front cathode and ultraviolet (UV) filtering layer. The gold nanoflowers are introduced in the device to increase the efficiency using localized surface plasmon resonance (LSPR) shown by plasmonic nanoparticles. We used GPVDM software to first optimize the cell, based on the geometry AZO/ZnO/PTB7:PC71BM/MoO3/Ag where AZO acts as the transparent conducting oxide (TCO) cathode and UV filter, zinc oxide (ZnO) behaves as the electron transport layer (ETL), Thieno[3,4 b]thiophene-alt-benzodithiophene: [6,6]-phenyl C71 butyric acid methyl ester (PTB7: PC71BM) mixture as the active layer, molybdenum trioxide (MoO3) as the hole transport layer (HTL) and silver (Ag) serves as the anode layer. By modelling, we find that the optimized device with maximum power conversion efficiency (PCE) includes 10 nm thick HTL, 200 nm thick photoactive layer and ETL thickness of 30 nm. Using the optimized thicknesses, we have fabricated three structurally identical inverted OSCs: first having AZO as the front cathode (AZO based device); second with ITO as the front cathode (ITO based control device); third includes AZO as cathode and plasmonic gold nanoflowers embedded inside the active layer (plasmonic assisted AZO based device). The AZO based device exhibited the PCE value of 6.19%, slightly less than the efficiency of 6.83% for ITO based control device. However, a remarkable increase in the lifetime was achieved for AZO based device under UV assisted acceleration ageing test. The stability enhancement of AZO based device is because of the UV filtering properties of AZO which prevent degradation in the device due to UV exposure. Also, the PCE of AZO based device was further enhanced to 7.01% when plasmonic gold nanoparticles were included in the active layer. This work provides a feasible way to develop an ITO free plasmonic assisted inverted organic solar cell to achieve cost-effectiveness, high efficiency and stability.

Fabrication of inverted organic solar cells on stainless steel substrate with electrodeposited and spin coated ZnO buffer layers

Polymer based organic solar cells (OSCs) are of tremendous interest as suitable candidates for producing clean and renewable energy in recent years. In this study, inverted OSCs on stainless steel (SS) substrate with zinc oxide (ZnO) as the electron selective transport layer (ESTL), are investigated, occupying bulk heterojunction blend of regioregular poly(3-hexylthiophene) (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM) as the active material and poly-(4,3-ethylene dioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) as the hole transport layer (HTL). The device structure is SS/ZnO/P3HT:PCBM/PEDOT:PSS/Au. ZnO films are prepared by spin coating and electrodeposition techniques, followed by annealing under ambient conditions. The insertion of ZnO layer between the SS substrate and active layer has improved short-circuit current (J sc), open-circuit voltage (V oc), fill factor (FF), and power conversion efficiency (PCE) compared to those of the reference cell without ZnO layer, achieving the highest efficiency of 0.66% for the device with spin coated ZnO from sol–gel technique. This enhancement can be attributed to the effective electron extraction and the increased crystallinity of ZnO after annealing treatments at higher temperatures as further confirmed by X-ray diffraction (XRD) and scanning electron microscope (SEM) analyses.

A Modified Sequential Deposition Route for High-Performance Carbon-Based Perovskite Solar Cells under Atmosphere Condition

Carbon-based hole transport material (HTM)-free perovskite solar cells have exhibited a promising commercialization prospect, attributed to their outstanding stability and low manufacturing cost. However, the serious charge recombination at the interface of the carbon counter electrode and titanium dioxide (TiO2) suppresses the improvement in the carbon-based perovskite solar cells’ performance. Here, we propose a modified sequential deposition process in air, which introduces a mixed solvent to improve the morphology of lead iodide (PbI2) film. Combined with ethanol treatment, the preferred crystallization orientation of the PbI2 film is generated. This new deposition strategy can prepare a thick and compact methylammonium lead halide (MAPbI3) film under high-humidity conditions, which acts as a natural active layer that separates the carbon counter electrode and TiO2. Meanwhile, the modified sequential deposition method provides a simple way to facilitate the conversion of the ultrathick PbI2 capping layer to MAPbI3, as the light absorption layer. By adjusting the thickness of the MAPbI3 capping layer, we achieved a power conversation efficiency (PCE) of 12.5% for the carbon-based perovskite solar cells.

DFT and TD-DFT Studies of 1,3,5-Tris (Dipheny1amino) Benzene Derivatives Based Hole Transport Materials: Application for Perovskite Solar Cells

The current study examined a series of 1,3,5-tris (diphenylamino) benzene derivatives used as hole transport materials in perovskite solar cells (HTM1-HTM9). DFT and TD/DFT with the B3LYP/6-311G basis set used for all calculations. The ground state geometry, frontier molecular orbital (FMO), photoelectric properties and reorganization energies and the absorption spectra were investigated. The energy levels of HOMO and LUMO orbitals were calculated for HTM1-HTM9, compared to all of the compounds under investigation and the spiro-OMeTAD, HTM 8 has the lowest HOMO energy level, indicating a favourable overlap with the MAPbI3 perovskite active layer.

Using ZnCo2O4 Nanoparticles as The Hole Transport Layer to Improve Long-Term Stability of Perovskite Solar Cells

Inorganic metal oxides with the merits of high carrier transport capability, low cost and superior chemical stability have largely served as the hole transport layer (HTL) in perovskite solar cells (PSCs) in recent years. Among them, ternary metal oxides gradually attract attention because of the wide tenability of the two inequivalent cations in the lattice sites that offer interesting physicochemical perperties. In this work, ZnCo2O4 nanoparticles (NPs) were prepared by a chemical precipitation method and served as the HTL in inverted PSCs. The device based on the ZnCo2O4 NPs HTL showed better efficiency of 12.31% and negligible hysteresis compared with the one using PEDOT:PSS film as the HTL. Moreover, the device sustained 85% of its initial efficiency after 240 hours storage under a halogen lamps matrix exposure with an illumination intensity of 1000 W/m2, providing a powerful strategy to design long-term stable PSCs for future production.