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A facile strategy was developed to simultaneously improve the performance and stability of perovskite solar cells (PSCs). It involves the dissolution of an ultranarrow bandgap material, (2,2′-((2Z,2′Z)-(((4,4,9,9-tetrakis (4-hexylphenyl)-4,9-dihydro-s-indaceno [1,2-b:5,6-b′] dithiophene-2,7-diyl) bis (4-((2-ethylhexyl) oxy) thiophene-5,2-diyl))bis(methanylylidene))bis(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene)) dimalononitrile (IEICO-4F)), in chlorobenzene (antisolvent), the use of the solution in the treatment of perovskite films during spin-coating, and the fabrication of solar cells using the treated perovskite films. IEICO-4F formed a charge transfer bridge at the perovskite/Spiro-OMeTAD interface and improved the charge extraction and transport. Furthermore, the addition of IEICO-4F facilitated the crystallization, improved the surface morphology, and enhanced the passivation of trap sites of perovskite films. Meanwhile, a reliable power conversion efficiency exceeding 20% for CH3NH3PbI3-based cells and 15.72% for CsPbBrI2-based all-inorganic PSCs was realized. These values surpass those of the control devices (i.e., 18.66% and 13.30%, respectively). [ABSTRACT FROM AUTHOR]

In inverted perovskite solar cells, poly(3,4-ethylene dioxythiophene) (PEDOT) and poly(styrene sulfonate) (PSS) are traditional hole transport materials. In such cells, functional improvement is becoming harder to achieve for the device. However, in this study, a novel process was found to be effective using the argon-plasma treatment, in which the ion cluster was used to scour the PEDOT:PSS surface instead of the traditional bombardment method. By an ideal plasma-generation power and treatment time (1800 J), the largest photoelectric conversion efficiency (PCE) of the device of PED (PEDOT:PSS surface being parallel to the plasma-generation electric field direction) reaches 14.8% with an improvement of 23.3% compared to the VED (vertical to the plasma electric field direction) device whose PCE is 13.31%, while the PCE of the reference is 12.0%. As per the physical mechanism, both PED and VED treatment can increase the surface free energy and roughness to result in a suitable hydrophilicity and larger grain size of the perovskite film. With the change in the ratio of PEDOT and PSS by the plasma treatment, the conductivity of the film also increases observably. Furthermore, since PED has the furrowing effect on the PEDOT:PSS surface, the ordered crystallization leads to perovskite films with few pinholes, and improves the abovementioned properties better than VED. [ABSTRACT FROM AUTHOR]

The crystalline quality of the perovskite film plays a key role in improving the optoelectronic properties and the performance of planar perovskite hybrid solar cells (PSCs). In this study, a methodology employing post-annealing microwave treatment (MPAT) for fine tuning the crystallization of perovskite films is proposed. It was found that the microwave induced electromagnetic waves result in the vibration of dipoles and ions at high frequencies in perovskite crystals, which catalyzes the Ostwald ripening process and results in good quality perovskite films. High quality perovskite films were obtained after being subjected to MPAT with 350 watts of power for 25 seconds. The resulting films, demonstrating an inverted solar cell architecture, and showed a champion efficiency of 13.39%. This was a significant improvement in the performance compared to those of the devices employing films without MPAT treatment (PCE = 11.5%). The MPAT provides a way to prepare high quality perovskite films that are of particular significance for the manufacturing of large area perovskite solar cells. [ABSTRACT FROM AUTHOR]

In this work, an efficient and stable inverted planar perovskite solar cell (PSC) with water additive has been prepared in ambient air. Adding moderate water additive to CH 3 NH 3 PbI 3−x Cl x precursor solution leads to growth in quality of CH 3 NH 3 PbI 3−x Cl x film, because the boiling point of water is lower than that of N, N-dimethylformamide. The annealing temperature of the CH 3 NH 3 PbI 3−x Cl x film is controlled to 105 °C (slightly higher than the boiling point of water) to obtain the dense perovskite film rapidly in ambient environment with ~ 40% relative humidity. The highest power conversion efficiency (PCE) of PSC with water additive is 14.02%, higher than that (11.17%) of the reference device without water additive. In addition, the aqueous CH 3 NH 3 PbI 3−x Cl x solution is transformed into the stable perovskite film through the method of rapid annealing. The stable CH 3 NH 3 PbI 3−x Cl x ·nH 2 O system can resist the decomposition of perovskite film and weaken iodide ion migration in PSCs, which enhance stability of the device under the atmospheric environment. After being stored in the air for 120 h, the PSC device with water additive still has an PCE of 12.01%, higher than that (1.64%) of the reference device. [ABSTRACT FROM AUTHOR]

This work proposes a new perovskite solar cell structure by inserting the double modified interlayers consisting of the 4,7-diphenyl-1,10-phenanthroline (Bphen) and cesium carbonate (Cs 2 CO 3 )-MoO 3 layer between perovskite (CH 3 NH 3 PbI 3−x Cl x )/PCBM (phenyl-C61-butyric acid methylester) and an Ag electrode. The double interlayers improve the photovoltaic efficiency to 15.59%, which is higher than that of reference devices with Bphen (13.41%) or alone, the champion PCE of 16.01% is obtained. The enhanced opening circuit voltage (V oc ) is ascribed as the main factor to improve the efficiency. Further studies show, the reduced work function of cathode by means of the Cs 2 CO 3 -MoO 3 could effectively extract the electrons and reduce the carrier recombination and thus result in a higher V oc . [ABSTRACT FROM AUTHOR]

This work reports an investigation on the performance improvement of bulk heterojunction polymer solar cells made of poly(3-hexylthiophene) and [6,6]-phenyl C-butyric acid methyl ester (P3HT:PCBM) blend system by introducing nickel nanoparticles (Ni NPs). Using the simplest cell structure, the addition ratio of 2 % of Ni NPs results in a remarkable increase in the light absorption and the short current, which brings an enhancement on power conversion efficiency with 25 % compared with the reference device. The analysis indicates that the electromagnetic surface wave generated from Ni NPs coupled with the photoactive layer forms surface plasmon resonance, which can result in a light trapping effect to increase the light absorption. As a conclusion, the inexpensive Ni NPs may provide an effect and alternative process on the performance improvement of the polymer solar devices. [ABSTRACT FROM AUTHOR]

A key issue for perovskite solar cells is the stability of perovskite materials due to moisture effects under ambient conditions, although their efficiency is improved constantly. Herein, an improved CH3NH3PbI3− xCl x perovskite quality is demonstrated with good crystallization and stability by using water as an additive during crystal perovskite growth. Incorporating suitable water additives in N, N-dimethylformamide (DMF) leads to controllable growth of perovskites due to the lower boiling point and the higher vapor pressure of water compared with DMF. In addition, CH3NH3PbI3− xCl x · nH2O hydrated perovskites, which can be resistant to the corrosion by water molecules to some extent, are assumed to be generated during the annealing process. Accordingly, water additive based perovskite solar cells present a high power conversion efficiency of 16.06% and improved cell stability under ambient conditions compared with the references. The findings in this work provide a route to control the growth of crystal perovskites and a clue to improve the stability of organic-inorganic halide perovskites. [ABSTRACT FROM AUTHOR]

Abstract: The effect of alkali treatment of Si nanowires (SiNWs) on the spectral response of solar cells was investigated using monochromatic incident photon-to-electron conversion efficiency spectroscopy. SiNWs were prepared on a substrate by metal-assisted etching and were then treated with NaOH/isopropanol. The results show that alkali treatment of SiNWs for 30s obviously improved the cell conversion efficiency. This was attributed to enhancement of the red light response and a decrease in surface reflectivity from 6% to ~2%. However, SiNW alkali treatment led to poor blue light response, which is a major limiting factor for efficient SiNW solar cells. To improve the photovoltaic properties of SiNW cells, a near-complete response over the whole solar spectrum is essential. [Copyright &y& Elsevier]

The Si nanowire array (SiNWA) was achieved by metal-assisted etching. The effect of alkali-treating of SiNWA on the photovoltaic performance of solar cells was investigated. We found that the post-chemical treatment of SiNWA on solar cells could reduce (i) the surface reflection and (ii) the thickness of “dead layer” so that the short-wavelength spectral response is enhanced. As a result, a solar-spectrum-averaged reflectance of less than 3 % has been reached, a 3-fold enhancement on the spectral response of post-treated SiNWA cell at the wavelength of 400 nm has been observed, together resulting in a remarkable improvement of 45 % in the conversion efficiency. [ABSTRACT FROM AUTHOR]