Optimization of Sb2S3 Nanocrystal Concentrations in P3HT: PCBM Layers to Improve the Performance of Polymer Solar Cells

Facile fabrication of crack-free TiO2 inverse opal thin-film and its application as electron transporting scaffold for efficient Sb2S3-sensitized solar cells

Uniform and crack-free TiO2 inverse opal thin-films were successfully fabricated by simple template immersion method in pre-hydrolyzed TiCl4 precursor solution even though it is difficult to fabricate crack-free inverse opals through conventional solution drop-casting sol-gel process. Here, mechanically robust polystyrene (PS) colloidal crystal template in which PS particles are linked by polyvinylpyrrolidone bridges, were immersed in pre-hydrolyzed TiCl4 precursor solution to infiltrate the templates without inducing defects. By repeated soaking and drying process, and subsequent calcination, non-uniform and crack defects-free TiO2 inverse opal thin-films were fabricated reproducibly because PS templates immersed in the precursor solution experienced consistent fluid flow into their pores at uniform precursor concentration together with suppressed capillary pressure during drying as a result of low infiltration rate per cycle. Also, as an improvement to conventional approach, this facile fabrication method is adaptable for industrial scale-up. The resulting well-developed porous TiO2 inverse opal thin-films were applied for photovoltaic clean energy conversion as electron transporting scaffolds in antimony sulfide (Sb2S3) sensitized solar cells which had high power conversion efficiency of 7.30 % (1 sun), 8.56 % (0.5 sun), and 8.34 % (0.1 sun); showcasing improved device performance over previously reported mesoporous Sb2S3-sensitized solar cells.

Surface oxygen vacancy-dependent molecular oxygen activation for propane combustion over α-MnO2

Oxygen vacancies (OV), as the sites of molecular oxygen adsorption and activation, play an important role in the catalytic combustion process of volatile organic compounds (VOCs). Revealing the relationship between OV concentration and molecular oxygen activation behavior is of significance to construct the efficient catalysts. Herein, α-MnO2 with different OV concentrations was prepared to investigate the molecular oxygen activation for C3H8 combustion. It is disclosed that the enhanced OV concentration in α-MnO2 induced the reconfiguration of surface metal atoms, resulting in the transformation of oxygen activation configuration from end-on mode to side-on mode. Oxygen molecules in side-on mode possessed more localized electron density and weaker coordination bond strength with surrounding Mn atoms, which were more favorable to adsorb C3H8 molecules and activate C-H bond for the improved combustion performance. This work provides a new understanding to reveal that the increased OV concentration contributes to more efficient VOCs combustion.

Effects of Solvent Additive and Micro-Patterned Substrate on the Properties of Thin Films Based on P3HT:PC70BM Blends Deposited by MAPLE

Lately, there is a growing interest in organic photovoltaic (OPV) cells due to the organic materials' properties and compatibility with various types of substrates. However, their efficiencies are low relative to the silicon ones; therefore, other ways (i.e., electrode micron/nanostructuring, synthesis of new organic materials, use of additives) to improve their performances are still being sought. In this context, we studied the behavior of the common organic bulk heterojunction (P3HT:PC70BM) deposited by matrix-assisted pulsed laser evaporation (MAPLE) with/without 0.3% of 1,8-diiodooctane (DIO) additive on flat and micro-patterned ITO substrates. The obtained results showed that in the MAPLE process, a small quantity of additive can modify the morphology of the organic films and decrease their roughness. Besides the use of the additive, the micro-patterning of the electrode leads to a greater increase in the absorption of the studied photovoltaic structures. The inferred values of the filling factors for the measured cells in ambient conditions range from 19% for the photovoltaic structures with no additive and without substrate patterning to 27% for the counterpart structures with patterning and a small quantity of additive.

1,4-Bis((9H-Carbazol-9-yl)Methyl)Benzene-Containing Electrochromic Polymers as Potential Electrodes for High-Contrast Electrochromic Devices

Four 1,4-bis((9H-carbazol-9-yl)methyl)benzene-containing polymers (PbCmB, P(bCmB-co-bTP), P(bCmB-co-dbBT), and P(bCmB-co-TF)) were electrosynthesized onto ITO transparent conductive glass and their spectral and electrochromic switching performances were characterized. The PbCmB film displayed four types of color variations (bright gray, dark gray, dark khaki, and dark olive green) from 0.0 to 1.2 V. P(bCmB-co-bTP) displayed a high transmittance variation (∆T = 39.56% at 685 nm) and a satisfactory coloration efficiency (η = 160.5 cm2∙C-1 at 685 nm). Dual-layer organic electrochromic devices (ECDs) were built using four bCmB-containing polycarbazoles and poly(3,4-ethylenedioxythiophene) (PEDOT) as anodes and a cathode, respectively. PbCmB/PEDOT ECD displayed gainsboro, dark gray, and bright slate gray colors at -0.4 V, 1.0 V, and 2.0 V, respectively. The P(bCmB-co-bTP)/PEDOT ECD showed a high ∆T (40.7% at 635 nm) and a high coloration efficiency (η = 428.4 cm2∙C-1 at 635 nm). The polycarbazole/PEDOT ECDs exhibited moderate open circuit memories and electrochemical redox stability. The characterized electrochromic properties depicted that the as-prepared polycarbazoles had a satisfactory application prospect as an electrode for the ECDs.

Organic Solar Cells Parameters Extraction and Characterization Techniques

Organic photovoltaic research is continuing in order to improve the efficiency and stability of the products. Organic devices have recently demonstrated excellent efficiency, bringing them closer to the market. Understanding the relationship between the microscopic parameters of the device and the conditions under which it is prepared and operated is essential for improving performance at the device level. This review paper emphasizes the importance of the parameter extraction stage for organic solar cell investigations by offering various device models and extraction methodologies. In order to link qualitative experimental measurements to quantitative microscopic device parameters with a minimum number of experimental setups, parameter extraction is a valuable step. The number of experimental setups directly impacts the pace and cost of development. Several experimental and material processing procedures, including the use of additives, annealing, and polymer chain engineering, are discussed in terms of their impact on the parameters of organic solar cells. Various analytical, numerical, hybrid, and optimization methods were introduced for parameter extraction based on single, multiple diodes and drift-diffusion models. Their validity for organic devices was tested by extracting the parameters of some available devices from the literature.