Water-Based Blend Nanoparticles of P3HT and PCBM for the Application in Organic Solar Cells

Effective Double Electron Transport Layer Inducing Crystallization of Active Layer for Improving the Performance of Organic Solar Cells

Interface modification plays an important role in enhancing the photoelectric conversion efficiency and stability of organic solar cells. In this work, alkali metal lithium chloride (LiCl) was introduced between indium tin oxide and polyethyleneimine ethoxylate (PEIE) to prepare a double-layer electron transport layer. Results show that the introduction of LiCl has dual functions. The first function is that LiCl can enhance conductivity, thereby facilitating charge collection. The second function is that the double-layer electron transport layer based on LiCl can induce the crystallization of active layer, thereby enhancing charge transport. Devices with LiCl/PEIE double layer achieve a high power conversion efficiency (PCE) of 3.84%, which is 21.5% higher than that of pristine devices (the PCE of pristine devices with pure PEIE interface layer is 3.16%).

Solar to hydrocarbon production using metal-free water-soluble bulk heterojunction of conducting polymer nanoparticle and graphene oxide

This work demonstrates the first example of interfacial manipulation in a hybrid photocatalyst based on poly(3-hexylthiophene-2,5-diyl) (P3HT) nanoparticle and graphene oxide (GO) bulk heterojunctions to efficiently reduce CO₂ into selective industrial hydrocarbons under gas-phase reaction and visible-light illumination. High selectivity of chemical products (methanol and acetaldehyde) was observed. Moreover, the hybrid photocatalyst's solar-to-fuel conversion efficiency was 13.5 times higher than that of pure GO. The increased production yield stems from the co-catalytic and sensitizing role of P3HT in the hybrid system due to its ability to extend light absorption to the visible range and improve interfacial charge transfer to GO. The hybrid P3HT-GO formed a type II heterojunction, and its static and dynamic exciton behaviors were examined using fluorescence spectroscopy and exciton lifetime mapping. A reduced fluorescence decay time was observed by interfacial manipulation for improved dispersion, indicating a more efficient charge transfer from the excited P3HT to GO. Thus, the conducting polymer nanoparticles, 2D nanocarbon, have demonstrated superior performance as a metal-free, non-toxic, low-cost, and scalable heterogeneous photocatalyst for CO₂ reduction to solar fuel, a solid-gas system.

Tuning the size and morphology of P3HT/PCBM composite nanoparticles: towards optimized water-processable organic solar cells

The function of an organic solar cell relies on making a contact surface between a donor and acceptor material. For efficient conversion of solar energy, this heterojunction must be maximized. Nanoparticulate systems already have a large surface-to-volume ratio per se. We increase the area of the heterojunction even further. Based on the miniemulsion process, colloidal particles are produced that contain both donor and acceptor material. Composite nanoparticles of Poly(3-hexylthiophene-2,5-diyl) and Phenyl-C61-butyric acid methyl ester (P3HT : PCBM) are prepared via the miniemulsion method. Here, the process parameters are tuned to optimize the efficacy of the composite nanoparticles. Depending on the surfactant concentration, the solvent and the processing temperature, we can tune the particle size and the morphology of the intraparticular heterojunction from Janus type to core-shell structures. Based on these findings, we finally identify the process parameters to achieve optimal solar cell performance.

Control of Shell Morphology in p-n Heterostructured Water-Processable Semiconductor Colloids: Toward Extremely Efficient Charge Separation

This article describes p-n heterostructured water-borne semiconductor naonoparticles (NPs) with unique surface structures via control of shell morphology. The shell particles, comprising PC60-[6,6]-phenyl-C61-butyric acid methyl ester (PC₆₁ BM) composite, having n-type semiconductor characteristics, notably influence the charge carrier behavior in the core-shell NPs. A one- or two-phase methodology based on a PC60 surfactant-water phase and PC₆₁ BM n-type semiconductor-organic phase provides highly specific control over the shell structure of the NPs, which promote their superior charge separation ability when combined with poly-3-hexyl-thiophene (P3HT). Moreover, the resulting water-borne NP exhibits shell morphology-dependent carrier quenching and stability, which is characterized via luminescence studies paired with structural analysis. Corresponding to the results, outstanding performances of photovoltaic cells with over 5% efficiency are achieved. The results suggest that the surrounding shell environments, such as the shell structure, and its electronic charge density, are crucial in determining the overall activity of the core-shell p-n heterostructured NPs. Thus, this work provides a new protocol in the current fields of water-based organic semiconductor colloids.

Photoactive Donor-Acceptor Composite Nanoparticles Dispersed in Water

A major issue that inhibits the large-scale fabrication of organic solar modules is the use of chlorinated solvents considered to be toxic and hazardous. In this work, composite particles of poly[N-9'-heptadecanyl-2,7-carbazole-alt-5,5-(4,7-di-2-thienyl-2',1',3'-benzothiadiazole] (PCDTBT) and [6,6]-phenyl C71 butyric acid methyl ester (PC₇₁BM) were obtained in water from a versatile and a ready-to-market methodology based on postpolymerization miniemulsification. Depending on the experimental conditions, size-controlled particles comprising both the electron donor and the electron acceptor were obtained and characterized using transmission electron microscopy (TEM), atomic force microscopy (AFM), small-angle neutron scattering (SANS), UV-visible absorption, and fluorescence spectroscopy. Intimate mixing of the two components was definitely asserted through PCDTBT fluorescence quenching in the composite nanoparticles. The water-based inks were used for the preparation of photovoltaic active layers that were subsequently integrated into organic solar cells.

Surfactant-free, low band gap conjugated polymer nanoparticles and polymer:fullerene nanohybrids with potential for organic photovoltaics

Stable, aqueous dispersions of nanoparticles based on the low band gap polymers poly [2,7-(9,9-dioctyl-fluorene)-alt-5,5-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)] (APFO-3) and poly [N-9'-heptadecanyl-2,7-carbazole-alt-5,5-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)] (PCDTBT) were prepared, using a flexible, surfactant-free reprecipitation method, and characterized by a variety of optical techniques. Light scattering measurements indicated average nanoparticle hydrodynamic diameters of approximately 40 nm. The particles presented wide-bandwidth absorption and photoluminescence excitation spectra with high absorption cross-sections on the order of 10(-12) cm(2). Nanoparticle emission spectra were significantly red-shifted, with decreased emission quantum yields and lifetimes, consistent with increased inter-polymer chain interactions in the condensed phase. Single particle photoluminescence studies highlighted the multi-chromophoric nature of the polymer nanoparticles and confirmed their favorable photostabilities. When the nanoparticles were doped with [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), the correspondence of photoluminescence emission quenching, quantum yield decreases, emission lifetime shortening, and increased non-radiative rates with increasing PCBM concentration suggested efficient photo-induced donor-to-acceptor charge transfer between the conjugated polymers and the fullerene dopants co-localized in the nanoparticle cores. Taken together, the data suggest that these surfactant-free hybrid nanomaterials may be useful for integration with future nanostructured organic photovoltaics technologies.