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Despite the performance improvement in perovskite solar cells (PSCs) when MXenes are employed as transport layers, device stability studies are still missing. Especially under real outdoor conditions where devices are subjected to the synergy of multiple stressors. In this work, functionalized 2D titanium carbide (Ti3C2) MXene is employed in normal PSC configuration, at the interface between the halide perovskite and the hole transport layer. The functionalization of the Ti3C2 MXene is made utilizing the same organic additive passivating the halide perovskite layer. The functionalizing strategy creates a continuous link between the MXene and the halide perovskite layer. Champion MXene‐based PSCs revealed a ≈22% efficiency, in comparison with the control device showing 20.56%. Stability analyses under ISOS protocols under different conditions (dark, continuous light irradiation and real outdoor analysis) reveal that the enhancement of the PSCs lifespan is always observed when the MXene layer is employed. Analysis under continuous light irradaition (ISOS‐L) reveal an almost 100% retention of the efficiency for the MXene‐modified device, and outdoor testing (ISOS‐O) carried out for > 600 h reveals a T80 of ≈600 h, while the control device degrades completely. To the best of the authors' knowledge, this is the first report of the stability assesment of MXene‐based PSCs carried out under real outdoor (ISOS‐O) conditions. [ABSTRACT FROM AUTHOR]

Surface passivation with organic halide salts is a powerful strategy to enhance the performance of perovskite solar cells. However, the inevitable formed in‐plane favored two‐dimensional perovskite layers with low carrier mobility and high binding energy inhibit the interfacial charge transfer within the device. Herein, a bulky fluorinated phenmethylammonium salt is designed and synthesized to passivate the perovskite film without forming 2D perovskites. A strong interaction which is induced by an electron donation from passivation agent to perovskite not only reduces the defects at the top surface of the perovskite, but also suppresses the recombination reaction at the buried surface due to a permeation of the organic halide salt. Moreover, the results of time resolved photoluminescence and confocal microscopy images suggest that the interfacial charge transfer speed and uniformity are enhanced. As a result, the efficiency of a small‐area device increases from 20.7 ± 0.9% to 22.8 ± 0.4% (aperture: 0.16 cm2). Moreover, a stabilized efficiency of 18.0% (aperture: 10.0 cm2) is achieved for larger‐area modules with 6‐series connected sub‐cells. Equally important, the non‐encapsulated modules show significantly improved stability at ambient conditions (ISOS‐D‐1). These significant improvements provided by a simple and reproducible procedure can be readily adopted in other types of devices. [ABSTRACT FROM AUTHOR]

Metal‐halide perovskite solar cells (PSCs) exhibit outstanding power conversion efficiencies (PCEs) when fabricated as mm‐sized devices, but creation of high‐performing large‐area modules that are stable on a sufficiently long timescale still presents a significant challenge. Herein, the quality of large‐area perovskite film is improved by using ionic liquid additives via forming a new Pb‐N bonding between the ionic liquid and Pb2+. This new bond can be modulated by a critical screening of the anion structure of the ionic liquid. The selected ionic liquid effectively reduces the defects of the perovskite films and markedly elongate their carrier lifetimes. As a result, a champion PCE of 24.4% for small‐area (0.148 cm2) devices and 20.4% for larger‐area (10.0 cm2) modules under AM 1.5G irradiation is achieved. More importantly, the modified devices retain 90% of their peak PCE after aging for 1900 h at 65 ± 5 °C (ISOS‐T‐1) and 80% after continuous light soaking for 750 h. The non‐encapsulated modules maintained 80% of their peak PCE after 1100 h of aging in the air with a relative humidity of 35 ± 5% and temperature of 25 ± 5 °C under dark (ISOS‐D‐1), showing great potential for future commercialization. [ABSTRACT FROM AUTHOR]

The in situ photoelectropolymerization technique is used for synthesizing poly(3,4-ethylenedioxythiophene) (PEDOT) and the effect of different doping anions on overall solar cell performance is examined. The results have shown that a careful selection of the doping anions and the use of their lithium salts have improved the overall cell efficiency

We report on the degradation of organic photovoltaic (OPV) cells in both indoor and outdoor environments. Eight different research groups contributed state of the art OPV cells to be studied at Pomona College. Power conversion efficiency and fill factor were determined from IV curves collected at regular intervals over six to eight months. Similarly prepared devices were measured indoors, outdoors, and after dark storage. Device architectures are compared. Cells kept indoors performed better than outdoors due to the lack of temperature and humidity extremes. Encapsulated cells performed better due to the minimal oxidation. Some devices showed steady aging but many failed catastrophically due to corrosion of electrodes not active device layers. Degradation of cells kept in dark storage was minimal over periods up to one year. [ABSTRACT FROM AUTHOR]

During the last few decades, and in some cases only the last few years, novel thin-film photovoltaic (PV) technologies such as dye-sensitized solar cells (DSSC), organic solar cells (OPV), and, more recently, perovskite-based solar cells (PSC) have been growing in maturity with respect to device performance and device stability. Together with new material systems, novel device architectures have also been introduced. Both parameters will have an effect on the overall device stability. In order to improve the understanding of degradation effects and how they can be prevented, stress testing under different conditions is commonly applied. By careful combination of stress factors and thorough analysis of photovoltaic parameter decaying curves, an understanding of the underlying degradation pathways can be gained. With the help of standardized and accelerated stress tests, as described in the ISOS-protocols, statements concerning application lifetimes can finally be made and compared among different labs. Once a photovoltaic technology has proven long lasting durability, the ultimate barrier for entering the commercial market are the IEC tests, taking a deeper look on overall safety and reliability, not only on durability. Here, the most prominent stress tests are reviewed, discussed and extended with respect to learning the most about photovoltaic device stability. [ABSTRACT FROM AUTHOR]

Five different indium-tin-oxide free (ITO-free) polymer solar cell architectures provided by four participating research institutions that all presented a laboratory cell performance sufficient for use in mobile and information and communication technology (ICT) were evaluated based on photovoltaic performance and lifetime tests according to the ISOS protocols. The comparison of the different device architectures was performed using the same active material (P3HT: PCBM) and tested against an ITO-based reference device. The active area was 1 cm2 and rigid glass or flexible polyester substrates were employed. The performance results were corroborated by use of a round robin methodology between the four participating laboratories (DTU/DK, ECN/NL, Frauenhofer ISE/DE, and the Holst Centre/NL), while the lifetime testing experiments were carried out in only one location (DTU). Five different lifetime testing experiments were carried out for a minimum of 1000 h: (1) shelf life (according to ISOS-D-1); (2-3) stability under continuous 1 sun illumination (1000 Wm−2, AM1.5G) at low (37 ± 3°C) and high (80 ± 5°C) temperatures (according to ISOS-L-1 and ISOS-L-2); (4) stability under continuous low-light conditions at 0.1 sun (100 Wm−2, AM1.5G, 32°C) (according to ISOS-LL); (5) continuous illumination (670 Wm−2, AM1.5G) at high temperature (65°C) and high humidity (50% RH) (according to ISOS-L-3). Finally, the upscaling compatibility of these device architectures based on the device photovoltaic behavior, stability and scalability were identified and we confirm that an architecture that presents a high score in only one aspect of the solar cell performance is not sufficient to justify an investment in upscaling. Many will require further technical development. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 944-954, 2013 [ABSTRACT FROM AUTHOR]

Vertically aligned ZnO nanorods (NR) are prepared by two different syntheses methods and applied on polymer solar cells (PSCs). The ZnO electrodes work as the electron transport layer with the P3HT:PCBM blend acting as the active material. Several organic blend solution conditions are optimized: concentration, solvent, and deposition speed. The effect of different NR electrode morphologies is analyzed on the solar cell performance and characterized by current-voltage curves and IPCE analyses. The photovoltaic performance of the solar cells was observed to be influenced by many factors, among them infiltration of the organic P3HT:PCBM blend within the ZnO NR layer. The infiltration of the active layer was monitored by cross section SEM and energy dispersive X-ray spectroscopy analyses. Our results show that higher power conversion efficiencies are achieved when shorter NRs lengths are applied. The best power conversion efficiency obtained was 2.0% for a 400 nm ZnO NR electrode. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013 [ABSTRACT FROM AUTHOR]

Abstract: In this work, we study the effect of the transparent conducting oxide (TCO) and the polymer applied (MEH-PPV or P3HT) on the photovoltaic properties of TCO/TiO2/polymer/Ag bi-layer solar cells. The solar cells were analyzed under inert atmosphere conditions resembling an encapsulated or sealed device. We demonstrate that the substrate applied, ITO or FTO, modifies the crystalline structure of the TiO2: on an ITO substrate, TiO2 is present in its anatase phase, on an FTO, the rutile phase predominates. Devices fabricated on an FTO, where the rutile phase is present, show better stability under inert atmospheres than devices fabricated on an ITO, anatase phase. With respect to the polymer, devices based on MEH-PPV show higher Voc (as high as 1V), while the application of P3HT results in lower Voc, but higher J sc and longer device stability. These observations have been associated to (a), the crystalline structure of TiO2 and (b) to the form the polymer is bonded to the TiO2 surface. In-situ IPCE analyses of P3HT-based solar cells show a red shift on the peak corresponding to TiO2, which is not present on the MEH-PPV-based solar cells. The latter suggest that P3HT can be linked to the TiO2 though the S-end atom, which results in devices with lower Voc. All these observations are also valid for devices, where the bare TiO2 is replaced by an Nb–TiO2. The application of an Nb–TiO2 with rutile structure in these polymer/oxide solar cells is the reason for their higher stability under inert atmospheres. We conclude that the application of TiO2 in its rutile phase is beneficial for long-term stability devices. Moreover there is an interplay between low Voc and J sc in devices applying P3HT, since power conversion efficiency can be partially canceled by their lower Voc in comparison with MEH-PPV. These findings are important for polymer/oxide solar cells, but also for organic solar cells, where a layer of semiconductor oxides are in direct contact with a polymer, like in an inverted or tandem organic solar cells. [Copyright &y& Elsevier]

Abstract: Solid-state dye sensitized solar cells (SSDSCs) applying mesoporous TiO2 electrodes sensitized with Ru complex dye Z907 and conducting organic polymers as the hole transport material (HTM) are prepared. We employ the in-situ photo-electrochemically polymerization technique (PEP) in order to obtain, in a single step, the conducting organic polymer on the TiO2/Dye electrode. We developed a modification of reported method which allows the polymer poly(3,4-ethylenedioxythiophene) (PEDOT) by different electrochemical techniques applying constant-voltage and constant-current methods. Polymer morphology and its influence on solar cell performance were studied. Overall conversion efficiency above 2% (AM 1.5, 100 mW cm−2) was obtained. [Copyright &y& Elsevier]

Abstract: Hybrid Solar Cells (HSC) applying Nb-TiO2 in direct contact with a conducting organic polymer, MEH-PPV, show higher stability than the bare TiO2-based HSC when analyzed under inert atmosphere conditions. IPCE analyses revealed that inert atmospheres affect directly the semiconductor oxide in the first stages of the analyses but photovoltaic performance stabilizes after several hours. A 20wt% Nb-doped TiO2 presented the highest stability and photovoltaic properties. The behavior has been attributed to the solubility limit of Nb within the TiO2 beyond 20wt% doping level where the co-existence of NbO2 is observed. The HSCs were analyzed under controlled N2 atmosphere and 1000W/m2 (AM 1.5) irradiation. [Copyright &y& Elsevier]

The applications of conducting organic polymers in combination with semiconductor oxides are promising candidates as active materials for air-stable hybrid electronic applications such as transistors, light emitting diodes or organic photovoltaics. In this work, we report our last results on the application of SnO2 thin films in all solid-state hybrid solar cells. We also compare the results with other five solar cells developed in our laboratories applying MEH-PPV and semiconductor oxides like TiO2, Nb2O5, ZnO, CeO2 or CeO2–TiO2. In this work, SnO2 thin films, obtained from sol–gel solutions, have been applied in HSC in a configuration ITO/SnO2 thin film/MEH-PPV/Ag. The effects of factors, such as UV light, polymer thickness, stabilization in the dark and performance under irradiation conditions, have been investigated. Open circuit voltage and short circuit current values were about −0.45 V and 0.17 mA/cm2, with fill factors around 30%. Photoaction spectra show the activity of the semiconductor oxide below 340 nm and about 490 nm for the polymer. Lifetime behavior of the HSC showed an initial increase in current density reaching a maximum after about 1 h of irradiation. Blocking the UV-wavelength range by the application of a filter showed no significant difference in HSC properties with respect to the sample without UV filter. Comparison with other 5 semiconductor oxides revealed a direct relation between semiconductor oxide applied and Voc from the solar cell. [ABSTRACT FROM AUTHOR]