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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]

Abstract: Solution-processable functionalized graphene (SPFGraphene) and functionalized multiwalled carbon nanotubes(f-MWCNTs) are introduced for heterojunction solar cell. The performance of the device has improved by the incorporation of both SPFGraphene and f-MWCNTs. The open-circuit voltage (V oc), short-circuit current density (J sc), fill factor (FF) and power conversion efficiency (η) were 0.67V, 4.7mA/cm2, 32%, and 1.05%, respectively. Here, we expect that SPFGraphene acts as exciton dissociation and provide percolation paths for electron transfer, whereas f-MWCNTs provide efficient hole transportation. SPFGraphene and f-MWCNTs incorporation yields better carrier mobility, easy exciton splitting, and suppression of charge recombination, thereby improving photovoltaic action. [ABSTRACT FROM AUTHOR]

Planar-structure perovskite solar cells have attracted more and more attention, because their simple and low-temperature preparation processing. However, the performance of perovskite solar cells is currently limited by defect-induced recombination at interfaces between perovskite and charge transport layers. In this work, a filmy poly methyl methacrylate (PMMA) layer introduced in Perovskite/Spiro-OMeTAD interface to passivate the interfacial and interganular defects, by which a high open-circuit voltage (1.18 V) is acquired, and the optimal device shows a steady-state power conversion efficiency of 20.5% and negligible hysteresis. Femtosecond transient absorption measurement confirms a significant reduction in non-radiative recombination for passivated devices. Mott-Schottky measurement indicates improved flat band potential and carrier density in passivated devices, consisting with the increased voltage. In addition, PMMA film can protect perovskite film from moisture and oxygen erosion. The unsealed device still maintains 95% of the initial efficiency under ambient conditions with 60% relative humidity for one month. This approach solves one of the main limitations of interfacial recombination and shows its potential to improve the performance of perovskite solar cells in the future. • An ultrathin polymer film is used to passivate the interfacial and intergranular defects in PSCs. • The modified PSC shows a steady-state power conversion efficiency of 20.5% and negligible hysteresis. • The fs-TA measurement is implemented for analyzing transfer and recombination dynamics of the photo-generated carrier. • The PMMA film plays the role of encapsulation which could protect perovskite film from moisture and oxygen erosion. [ABSTRACT FROM AUTHOR]

SnO 2 electron transport layers (ETLs) had an essential role in the n-i-p structure of perovskite solar cells. Improving the quality of the electron transport layer and enhancing interfacial contacts were key factors in the fabrication of high-performance perovskite solar cells. Therefore, a non-ionic polymeric polyacrylamide (PAM) modified SnO 2 colloidal solution with improved clustering of SnO 2 nanoparticles was presented to form a uniform and dense SnO 2 electron transport layer. The results demonstrated that no pinhole pores were found at the interface where the PAM-modified electron transport layer and the light absorbing layer came into contact, a structure that facilitated carrier transport and reduced carrier recombination at the interface location. Further beneficial effects were revealed by femtosecond Fs-TA measurements and trap of states (tDOS) analysis, where the carrier lifetime τ 2 decreased from 306.7 ps to 137.8 ps and the trap density of states of the film also decreased significantly. Correspondingly, the SnO 2 -PAM device exhibited an optimum efficiency of 21.61 %. Fantastic device stability was obtained due to the interaction of excellent contact at the SnO 2 /FAPbI 3 interface, and 85 % of the initial efficiency was maintained when placed in air for 1000 h for photo-aging tests, thereby improving the stability of FAPbI 3 grains. This method of improving the quality of tin oxide colloidal solutions provided a novel and simple way to prepare efficient perovskite solar cells. [ABSTRACT FROM AUTHOR]

Abstract: Herein we report a study of the doping of the poly(2-methoxy-5-(30,70-dimethyloctyloxy)-1,4- phenylenevinylene) (MDMO-PPV), poly (3-oc tylthiophene) (P3OT), to the organic photovoltaic devices based on poly (3-hexylthiophene) (P3HT) and graphene derivative bulk heterojunction structure (BHJ). The addition of the donor polymers to P3HT:Graphene BJT solar cells resulted in a more broad absorption range. The interrelationships between UV–vis absorption, fill factor (FF), energy conversion efficiency (ECE) and current density have been simulated. Dependency of the open-circuit voltage (Voc) was based on different doped donors, which is due to the band structure of BHJ where the energy level difference between the highest occupied molecular orbital (HOMO) of the co-donors and the lowest occupied molecular orbital (LUMO) of the solution-processable functionalized graphene oxide (SPFGO) as acceptor was increased. The investigation indicated that the ECE of the co-donors:SPFGO BHJ solar devices with moderate doped donor amount can be influenced by the change of molecular packing structure, which can be interpreted in terms of incorporating doped donor. The XRD investigation of the complex donors/graphene BHJ solar device showed a well-organized intraplane structure with lamellae oriented normal to the substrate. In addition, The SEM investigation indicated the surface roughness morphology of the hybrid active layer film. [Copyright &y& Elsevier]