33 research outputs found
Enquêtes vers plus de performance et plus de stabilité : cellules solaires hybrides en pérovskite traitées en solution
No full textIn this Ph.D. thesis,I have been focused to investigate optimizations and strategies concerning the electron transportlayer (ETL),the hybrid perovskite active layer, and their interfaces in functional perovskite solar cells. On the investigatior of ETLs, I have performed two works: One is on the comparison of a simplified ETL-free planar perovskite solar cells,architecture to that with a planar TiO2 ETL (described in Chapter 2); Another work is on the comparison of perovskite,solat cells with well-oriented one-dimension TiO2 nanocolumn (NA) ETL to those with a planar TiO2 ETL (Chapter 3).On,the investigations of the perovskite active layer, mixed-cation and mixed-halide perovskite was applied into three,relevant works: (1) I optinized and maximized the grain size of the perovskite active layer (Chapter 2); (2) I studied nano-,structured hybrid perovskite fims and their light-harvesting enhancement (Chapter 6): (3) I investigated the thermal,properties of mixed-cation perovskite thin films to understand their improved thermal stability compared to,methylammonium lead iodide (MAPbi3) perovskite (Chapter 4). In addition, I studied passivation methods to alleviate the interfacial charge recombination and to improve the stability of perovskite solar cells (chapter 5).Dans cette thèse de doctorat, je me suis concentré sur l'optimisation et les stratégies concernant la couche de transport d'électrons (ETL), la couche active à base de pérovskite hybride et leurs interfaces dans les cellules solaires fonctionnelle,de pérovskite. En ce qui concerne l'étude des ETL, j'ai réalisé deux travaux : l'un porte sur la comparaison d'une architecture simplifiée de cellules solaires planaires à base de pérovskite sans ETL avec celle d'un ETL plan en TiO2 (décrit au chapitre 2) ; un autre travail porte sur la comparaison des cellules solaires à base de pérovskite avec des nanocolonnes de Ti02(NA) orientées à celles comportant simplement une ETL de TiO2 plane et non nanostructurée (chapitre 3). Lors des recherches sur la couche active de pérovskite, la pérovskite à cations mixtes et aux halogénures mixtes a été utilisée,dans trois axes de travail distincts. J'ai tout d'abord optimisé et maximisé la taille des grains de la couche active de pérovskite (chapitre 2). Ensuite, j'ai étudié des films de pérovskite hybride nano-structurés et leur amélioration au niveau de la collection de la lumière (chapitre 6). J'ai aussi étudié les propriétés thermiques des films minces de pérovskite à cation mixte et j'ai notamment déterminé leur conductivité et leur diffusivité thermique. L'étude contribue à comprendre leur meilleure stabilité thermique par rapport aux pérovskite à base d'iodure de plomb de méthylammonium (MAPbI3) (voir chapitre 4). Enfin, j'ai étudié les méthodes de passivation pour atténuer la recombinaison de la charge interfaciale et pour améliorer la stabilité des cellules solaires de pérovskite (chapitre 5)
Enquêtes vers plus de performance et plus de stabilité : cellules solaires hybrides en pérovskite traitées en solution
No full textIn this Ph.D. thesis,I have been focused to investigate optimizations and strategies concerning the electron transportlayer (ETL),the hybrid perovskite active layer, and their interfaces in functional perovskite solar cells. On the investigatior of ETLs, I have performed two works: One is on the comparison of a simplified ETL-free planar perovskite solar cells,architecture to that with a planar TiO2 ETL (described in Chapter 2); Another work is on the comparison of perovskite,solat cells with well-oriented one-dimension TiO2 nanocolumn (NA) ETL to those with a planar TiO2 ETL (Chapter 3).On,the investigations of the perovskite active layer, mixed-cation and mixed-halide perovskite was applied into three,relevant works: (1) I optinized and maximized the grain size of the perovskite active layer (Chapter 2); (2) I studied nano-,structured hybrid perovskite fims and their light-harvesting enhancement (Chapter 6): (3) I investigated the thermal,properties of mixed-cation perovskite thin films to understand their improved thermal stability compared to,methylammonium lead iodide (MAPbi3) perovskite (Chapter 4). In addition, I studied passivation methods to alleviate the interfacial charge recombination and to improve the stability of perovskite solar cells (chapter 5).Dans cette thèse de doctorat, je me suis concentré sur l'optimisation et les stratégies concernant la couche de transport d'électrons (ETL), la couche active à base de pérovskite hybride et leurs interfaces dans les cellules solaires fonctionnelle,de pérovskite. En ce qui concerne l'étude des ETL, j'ai réalisé deux travaux : l'un porte sur la comparaison d'une architecture simplifiée de cellules solaires planaires à base de pérovskite sans ETL avec celle d'un ETL plan en TiO2 (décrit au chapitre 2) ; un autre travail porte sur la comparaison des cellules solaires à base de pérovskite avec des nanocolonnes de Ti02(NA) orientées à celles comportant simplement une ETL de TiO2 plane et non nanostructurée (chapitre 3). Lors des recherches sur la couche active de pérovskite, la pérovskite à cations mixtes et aux halogénures mixtes a été utilisée,dans trois axes de travail distincts. J'ai tout d'abord optimisé et maximisé la taille des grains de la couche active de pérovskite (chapitre 2). Ensuite, j'ai étudié des films de pérovskite hybride nano-structurés et leur amélioration au niveau de la collection de la lumière (chapitre 6). J'ai aussi étudié les propriétés thermiques des films minces de pérovskite à cation mixte et j'ai notamment déterminé leur conductivité et leur diffusivité thermique. L'étude contribue à comprendre leur meilleure stabilité thermique par rapport aux pérovskite à base d'iodure de plomb de méthylammonium (MAPbI3) (voir chapitre 4). Enfin, j'ai étudié les méthodes de passivation pour atténuer la recombinaison de la charge interfaciale et pour améliorer la stabilité des cellules solaires de pérovskite (chapitre 5)
Luminescence enhancement effects on nanostructured perovskite thin films for Er/Yb-doped solar cells
No full textRecent attempts to improve solar cell performance by increasing their spectral absorption interval incorporate up-converting fluorescent nanocrystals on the structure. These nanocrystals absorb low energy light and emit higher energy photons that can then be captured by the solar cell active layer. However, this process is very inefficient and it needs to be enhanced by different strategies. In this work, we have studied the effect of nanostructuration of perovskite thin films used in the fabrication of hybrid solar cells on their local optical properties. The perovskite surface was engraved with a focused ion beam to form gratings of one-dimensional grooves. We characterized the surfaces with a fluorescence scanning near-field optical microscope, and obtained maps showing a fringe pattern oriented in a direction parallel to the grooves. By scanning structures as a function of the groove depth, ranging from 100 nm to 200 nm, we observed that a 3-fold luminescence enhancement could be obtained for the deeper ones. Near-field luminescence was found to be enhanced between the grooves, not inside them, independent of the groove depth and the incident polarization direction. This indicates that the ideal position of the nanocrystals is between the grooves. In addition, we also studied the influence of the inhomogeneities of the perovskite layer and we observed that roughness tends to locally modify the intensity of the fringes and distort their alignment. All the experimental results are in good agreement with numerical simulations.The authors acknowledge the support from the DIM Nano-K
program from “Region Ile de France”, from the Idex Paris
Sciences & Lettres through the grant ANR-10-IDEX-0001-02 PSL,
from the CNRS and the CSIC through the Spanish-French
program PICS (grant SolarNano #PICS07687 and
#PIC2016FR2), and the PROCES project (ANR-17-CEO5-0028-
01). They also acknowledge the service from the MiNa Laboratory
at IMN, which is funded by CM (project S2018/NMT-4291
TEC2SPACE), MINECO (project CSIC13-4E-1794) and EU
(FEDER, FSE).Peer reviewe
Thermal conductivity and diffusivity of triple-cation perovskite halide materials for solar cells
No full textInternational audienceWe report on the measurement of the thermal conductivity and the thermal diffusivity by the technique of modulated thermoreflectance microscopy on a mixed-cation perovskite material [Cs 0.05 (formamidinium 0.83 methylammonium 0.17) 0.95 Pb(I 0.83 Br 0.17) 3 ] widely applied for solutionprocessed perovskite solar cells. Such materials are supposed to present an improved thermal stability compared to methylammonium-based single cation perovskites. Our measurements are performed on perovskite/TiO 2 /SnO 2 :F/SiO 2 structures, with perovskite thicknesses ranging between 250 nm and 1000 nm. This configuration is the one of a real solar cell, with the same substrate and intermediate layers than an operating device. We measured a thermal conductivity k per of 0.26 0.03 W m-1 K-1 and a thermal diffusivity D per of 3.5×10-7 0.5 m 2 s-1. The value for the thermal conductivity is comparable to the one measured on single cation perovskites which is generally in the 0.2-0.6 range. The value for the thermal diffusivity was not reported previously
Synergistic Dual-Halide Anion Engineering for Efficient Interface Passivation in 1.68 eV Wide-Bandgap Perovskite Solar Cells for Indoor Photovoltaics
No full textInternational audienceWide-bandgap (1.68 eV) perovskite solar cells (PSCs) are considered promising candidates for indoor photovoltaics due to their favorable optical properties. However, their power conversion efficiency (PCE) is significantly constrained by large open-circuit voltage (V OC ) losses, which primarily originate from intrinsic halide vacancy defects and uncoordinated Pb 2+ located at the surface and grain boundaries of the perovskite films. Additionally, the energy level mismatches at the perovskite/electron transport layer (ETL) interface further aggravate V OC losses by promoting non-radiative recombination. Herein, we report a synergistic dual-halide interface passivation strategy based on methylammonium iodide (MAI) and methylammonium chloride (MACl), in which the two halides play complementary and mechanistically distinct roles. MAI effectively reacts with and converts residual surface PbI 2 into the perovskite phase, while simultaneously passivating iodine-related vacancy defects. In parallel, MACl induces beneficial chloride incorporation at the 3 interface, enabling slight bandgap broadening and producing a favorable vacuum-level shift that optimizes energy-level alignment between the perovskite and electron transport layer. When applied together, MAI and MACl deliver a cooperative passivation effect, substantially suppressing non-radiative recombination, prolonging carrier lifetimes, and facilitating more efficient charge extraction. As a result, the optimized 1.68 eV PSCs achieve a notable PCE of 20.41% with a V OC of 1.262 V under standard AM 1.5G illumination, surpassing the untreated counterparts that achieve 18.48% with a V OC of 1.169 V. More importantly, under indoor lighting conditions, the modified PSCs exhibit outstanding performance, delivering PCEs of 36.74% and 32.36% under 1000 lux and 200 lux LED illumination, respectively, demonstrating their strong potential for indoor photovoltaics
Hybrid plasmonic gold-nanorod–platinum short-wave infrared photodetectors with fast response
No full textInternational audienceShort-wave infrared (SWIR) photodetectors, sensitive to the wavelength range between 1 and 3 μm, are essential components for various applications, which constantly demand devices with a lower cost, a higher responsivity and a faster response. In this work, a new hybrid device structure is presented for SWIR photodetection composing a coupling between solution-processed colloidal plasmonic gold (Au) NRs and a morphology-optimized resistive platinum (Pt) microwire. Pt microwires harvest efficiently the photothermal effect of Au NRs and in return generating a change of device resistance. A fast photon-heat-resistance conversion happens in these Au-NRs/Pt photodetectors exhibiting a response (rise) time of 97 μs under the illumination of a λ = 1.5 μm laser. Clear photoresponse can be observed in these devices at a laser illumination with a modulation frequency up to 50 kHz. The photoresponsivity of the current devices reached 4500 Ω W−1 under a laser power of 0.2 mW, which is equivalent to a responsivity of 340 mA W−1 under a DC bias of 1 V. A series of mapping experiments were performed providing a direct correlation between Au NRs and the device zone where resistance change happens under a laser illumination modulated at different frequencies
Photothermal‐Induced Electrical Behavior of Micron‐Sized Platinum Structures and Their Efficient Photodetection
No full textInternational audiencePhotothermal effects have recently been widely investigated for applications in the fields of biomedicine, physics, and chemistry. Unfortunately, only a few reports describe their potential use in ultrafast photodetectors. Herein, direct evidence for ultrafast photothermal‐induced electrical behavior of a platinum microwire (Pt MW) illuminated by a focused laser beam and modulated at different frequencies (329 Hz, 10, 50, and 150 kHz) is provided. The obtained electrical behavior images indicate that Pt‐based structures can be used to develop a new type of photodetector, namely, a photo‐thermo‐electric (PTE) detector. A high photoresponsivity of 0.3 mA W −1 and a fast response time of ≈50 μs on a single 1 μm wide Pt PTE detector are obtained. To further amplify the PTE effect of Pt MW, an integrated array of Pt MWs and a coating of gold nanorods is combined into a hybrid PTE detector, achieving a higher responsivity close to 100 mA W −1 , which is 300 times higher than that of a single Pt MW PTE detector. These results confirm that Pt‐based PTE devices are promising candidates for efficient and fast‐response photodetectors
Solution-processed flexible n-type S-doped Ag2Se thermoelectric generators for near-ambient-temperature energy harvest†
No full textInternational audienc
Upconversion nanoparticles extending the spectral sensitivity of silicon photodetectors to λ = 1.5 μ m
No full textInternational audienceThe telecommunication wavelength of = 1.5 µm has been playing an important role in various fields. In particular, performing photodetection at this wavelength is challenging, demanding more performance stability and lower manufacturing cost. In this work, by integrating solution-processed Er 3+ doped NaYF4 upconversion nanoparticles (UCNPs) onto a silicon photodetector, UCNPs/Si hybrid photodetectors (hybrid PDs) are presented. Upon optimization, we demonstrated that a layer of UCNPs can well lead to an effective spectral sensitivity extension without scarification of the photodetection performance of the Si photodetector in the visible and near-infrared (near-IR) spectrum. Under the = 1.5 µm illumination, the hybrid UCNPs/Si-PD exhibits a room-temperature detectivity of 6.15 × 10 12 Jones and a response speed of 0.4 ms. These UCNPs/Si-PDs represent a promising hybrid strategy towards the quest of low-cost and broad-band photodetection sensitive from the visible down to the shortwave infrared spectrum
Enhancing the Efficiency and Stability of Triple-Cation Perovskite Solar Cells by Eliminating Excess PbI2 from the Perovskite/Hole Transport Layer Interface
No full text
