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In this paper, we report a simple and highly reproducible strategy to fabricate a high-performance hysteresis-free organic-inorganic based perovskite solar cell (PSC). A single-step, fast deposition-crystallization method has been adopted for preparing MAPbI 3 based perovskite film. The role of ethoxyethane as an anti-solvent and the importance of deposition time in film crystallization have been investigated in detail. The solvent deposition time is observed to have a significant impact on the crystal growth and performance of PSCs. Intensive characterization, which includes scanning electron microscopy, UV–visible spectroscopy, X-ray diffraction studies and photovoltaic characterization, has been carried out to attribute the improved performance. In addition, the influence of FK209 Co(III) complex doped in organic hole transporting material for better charge extraction and transportation in PSC has been discussed in detail. This proposed strategy, involving a co-solvent deposition time of 10 s and 1.3% doping of FK209 Co (III) complex, provides a high 90% reproducible, hysteresis-free PSC with an average power conversion efficiency of 13.3% corresponding to an increment in photocurrent density (J sc ) by 31% and open circuit voltage (V oc ) by 6%. [ABSTRACT FROM AUTHOR]

Bismuth sulfide (Bi 2 S 3 ) is an attractive potential replacement for lead sulfide (PbS) due to its low toxicity and near infrared absorption spectrum. In this work, we report the photovoltaic characteristics of cadmium sulfide (CdS) and Bi 2 S 3 quantum dots (QDs) sensitized solar cells. The QDs were grown by the successive ionic layer adsorption and reaction (SILAR) method. The number of cycles was varied in order to optimize the photoconversion efficiency. Using a photovoltaic device with the structure TiO 2 /CdS/ZnS as our reference, we obtained increments in the short circuit current (J sc ) from 7.9 to 9.3 mA/cm 2 , the fill factor (FF) from 41.9 to 53.7%, and the photoconversion efficiency (η) from 1.7% to 2.52% for the configuration TiO 2 /CdS/Bi 2 S 3 /ZnS. This enhancement is explained by an augmented absorption spectral range and a favorable energy level diagram. Electrochemical impedance measurements were performed to better understand the carrier recombination and transport processes. [ABSTRACT FROM AUTHOR]

[Display omitted] • JV curves show how MABr improves long-term performance. • EQE and EIS show the physical origin of the improvement. • MABr permits the formation of benefic photoactive phases. In this study, perovskite solar cells with a structure Cs y FA 1-x MA x CS 0.05 Pb(I 1.05-x Br x) 3 , with X = 0 (no doping was added to the base structure CsFAPbI 3) and X = 0.085 (CsFAPbI 3 was doped with 8.5% MABr 3) were prepared and were subjected to a 60 days ageing process (15 days under vacuum conditions followed by 45 days under room conditions) to study their stability. J-V curves showed that after the 60 days, the cells with no MABr3 only had 50.32% of the original efficiency remaining, while the samples with 8.5% MABr 3 had 92.89% of the original efficiency, being the J sc the main parameter that was affected during the ageing period. IPCE measurements suggest the formation of Cs segregates, that maintain or even increase the J sc. According to electrochemical impedance studies, these segregates could be promoted by the lower ionic movement resistance in the 8.5% MABr 3 samples, which may allow to re-arrange the atoms of the crystalline structure in a benefic way. This work is of great importance because it helps to understand how the doping affects the degradation processes, while showing how Impedance Spectroscopy can be used to characterize the changes in the electrical and ionic dynamics of the solar cells. [ABSTRACT FROM AUTHOR]

Highlights • An efficiency of 10% was obtained with the inverted perovskite configuration under ambient condition. • The anti-solvent method was used to fabricated the perovskite film for solar cells. • The morphological, optic and photovoltaic analyses indicate that the right combination of these two parameters. Abstract Organic-inorganic inverted perovskite solar cells have been analyzed. This structure uses organic semiconductors as electron and hole selective electrodes and the perovskite as light harvesting layer. The anti-solvent deposition method is a frequently used techniques in the elaboration of conventional perovskite solar cells (FTO/TiO 2 /CH 3 NH 3 PbI 3 /Spiro-OMetad/Au). However, the anti-solvent method is seldom used in the inverted structure. In this work, we use the anti-solvent method to fabricate the perovskite film for solar cells in the ITO/PEDOT:PSS/CH 3 NH 3 PbI 3 /PC 61 BM/Ag configuration, systematically studying the effect of the anti-solvent dripping time and the relative humidity in cell fabrication and performance. The morphological, optical and photovoltaic analyses indicate that the right combination of these two parameters will result in a preferential crystal growth in the (1 1 0) orientation. This allows the formation of homogeneous pinhole-free films that enhance light harvesting and reduce charge-carrier leakage, hence increasing short circuit current and fill factor to obtain a photo-conversion efficiency of about ∼10%. [ABSTRACT FROM AUTHOR]

• The effects of external temperature exposure on perovskite solar cells are reported. • Fast degradation and disordered recrystallization generate pinholes and defects. • Pinholes and defects increase charge leakage and recombination, reducing the PCE. In this work, the effects of external temperature exposure on perovskite solar cells are reported. Experimental solar cells, with the configuration FTO/c-TiO 2 /m-TiO 2 /CH 3 NH 3 PbI 3 /Spiro-OMETAD/Au, were fabricated and exposed to different external temperatures (25, 40, 60 and 70 °C) for four hours. The objective was to compare the effects of external temperature exposure on perovskite solar cells. The thin films were characterized using SEM, XRD and absorption spectra. The solar cells were characterized obtaining their J-V curves, and using curve simulations to quantify changes in the working mechanisms of the cells. Experimental results indicate that samples exposed to temperatures under 40 °C suffer a decrease in PCE, mainly due to a reduction in FF but deaden by an increase in J sc. In addition, when the samples are exposed to higher temperatures, there is a general decrease in all photovoltaic parameters resulting in a considerable reduction in PCE. Simulations indicate that degradation of the cells starts at ambient temperature with the dissolution of the perovskite to form PbI 2 which introduces trap levels which reduce the FF. However, if the temperature is kept below 40 °C, the perovskite film can recrystallize inducing grain coalescence which reduces leakage and improves conductivity. This in turn produces an increase of J sc and a reduction of FF decay. Thus, decreasing lost performance and preserving about 80% of the original efficiency. On the other hand, if the cell is exposed to a temperature above 40 °C, the degradation processes accelerate, recrystallization becomes disordered resulting in the formation of pinholes and defects. These defects, coupled with a higher amount of PbI 2 , will result in reduction of J sc , V oc and FF, reducing the PCE. [ABSTRACT FROM AUTHOR]

In this work, we demonstrate an enhancement of photocurrent in QDSSCs based on CdS (QDs)/CdSe Quantum rods (QRs)/CdSeTe (QDs) heterostructure due to the increased photon harvesting in the VIS-NIR region. The photo-conversion efficiency increased from 2.7% up to 6.5% when CdSe QRs and CdSeTe QDs were added in the reference cell: TiO 2 /CdS/ZnS and the devices reached a maximum photocurrent of 21.5 mA cm −2 . This outstanding performance was caused by a broadening of the light absorption in the VIS and NIR regions, this in turn, was produced by the presence of CdSe QRs and CdSeTe QDs in the cells. The use of additional SiO 2 layer in the solar cell that contained CdSe QRs and CdSeTe QDs allowed us to improve the efficiency of the cells even more (up to 7.4%), since it decreased the recombination rate produced by defects and interfaces in the QDs. Moreover, the effect on the solar cells performance was studied as the size of the CdSeTe QDs introduced into them increases and found that both, the values of photocurrent and efficiency are enhanced as the size of the CdSeTe increases. We associated this improvement of performance to the increase of light absorption in the NIR region as the size of the CdSeTe QDs increases. Hence, our results suggest that the strategy of adding CdSeTe QDs with different sizes together with CdSe QRs is promising to enhance the efficiency of QDSSCs. [ABSTRACT FROM AUTHOR]

The development of up-scalable and high-throughput methodologies to fabricate high-efficiency lead halide perovskite solar cells (PSCs) based on α-phase formamidinium lead iodide (FAPbI 3) is one of the main challenges of making solar energy economical. In this context, PSCs based on α-phase formamidinium lead iodide (FAPbI 3) are receiving special attention as this perovskite has the highest theoretical photoconversion efficiency (PCE). This manuscript reports an easy, fast and environmentally-friendly way to prepare α-FAPbI 3 black powders by a microwave-assisted synthesis and their application in solar cells. The α-FAPbI 3 powders consist of micrometric particles that can be stored for weeks in a closed vial at ambient conditions. This technique presents an enormous potential for upscaling FAPbI 3 powders synthesis prerequisite necessary for large scale commercialization. The performance of the presynthesized FAPbI 3 -based solar cell was comparable with that of PSCs fabricated with the conventional procedure from precursors solutions, leading to a maximum PCE value of 18.15%, with an V OC =1.07 V, a J sc =24.28 mA/cm2 and an FF=70%. The presynthesized FAPbI 3 -based solar cell was further modified through the addition of methylammonium chloride (MACl) in order to study the generality of the approach. The optical band gap for the presynthesized perovskite shifted from ∼1.43 eV to ∼1.55 eV with the MACl addition (30 mol%), indicating the formation of a mixed methylammonium and formamidinium based perovskite material (MAFAPbI 3). In addition, the incorporation of MACl led to an increase in the grain size and the disappearance of the residual δ-phase perovskite, thus improving the efficiency of the final device. [ABSTRACT FROM AUTHOR]