Cold air quench control of local crystallization environment in fully air-processed carbon-based perovskite solar cells

Performance of low-cost mixed cationic carbon-based solar cells prepared through compositional engineering under ambient conditions

17.46% efficient and highly stable carbon-based planar perovskite solar cells employing Ni-doped rutile TiO2 as electron transport layer

Carbon based perovskite solar cells (C-PSCs) have attracted much attention because of their high stability and low-cost of production. However, due to the high interfacial resistance and the low energy level matching between perovskite and carbon electrodes, the maximum power conversion efficiency (PCE) is less than that of the metal-based perovskite solar cells. In this paper, a carbon-based perovskite solar cell is fabricated with the device structure of FTO/c-TiO2/m-TiO2/CH3NH3PbI3/Carbon. The perovskite films and carbon based perovskite solar cells are characterized by scanning electron microscope, atomic force microscope, X-ray diffraction (XRD), UV-Vis absorption spectrum, the steady-state spectrum, the time-resolved PL (TRPL) spectrum, and an electrochemical workstation. In addition, the internal mechanism of the efficiency improvement of carbon-based perovskite solar cell is discussed in depth. Then, the rotation speeds of mesoporous TiO2 layer (TiO2 paste diluted by ethanol with mass ratio of 1:4) are 1500, 1600, 1700 and 1800 r/min and the speeds of perovskite layer (CH3NH3I and PbI2 at a 1:1 molar ratio are stirred in a mixture of DMF and DMSO (9:1, v/v)) are 2000, 3000, 4000 and 5000 r/min; When the speed of m-TiO2 layer is 1700 r/min and the speed of perovskite layer is 4000 r/min, the mesoporous TiO2 layer thickness is about 500 nm, Thickness of CH3NH3PbI3 capping layer is about 400 nm. The cooperation of these two layers eventually leads to the high-quality perovskite with enlarged grain size, prolonged photoluminescence lifetime, lowered defect density, increased carrier concentration, and the finally enhanced photovoltaic performance. The device obtains the highest PCE of 11.11% with an open circuit voltage (Voc) of 0.93 V, a current density (Jsc) of 21.75 mA/cm2 and fill factor (FF) of 55%. At the same time, the stability of the carbon-based perovskite solar cell is also studied. The XRD is used for initial perovskite and the perovskite after 15 days to investigate the photo- and humidity stability of the full cells without encapsulation. The device exhibits excellent air stability with only 5% degradation when aged in ambient air at room temperature with 40%-50% humidity without any encapsulation after 15 days, which is better than the metal based perovskite solar cell. Our results open the way for making cost-efficient and stable PSCs toward market deployment.

Carbon-based perovskite solar cells (PSCs) are fast developing toward large-scale production. In this study, graphene oxide (GO) was applied as a hole transport material (HTM) for carbon-based mesoscopic PSCs with n-i-p structure. The GO was prepared using a simple Hummer’s method, while the carbon counter electrode was deposited using a doctor blade and heated at a temperature of 120 °C. The mesoscopic carbon-based PSCs with various GO dispersion (1.0, 1.5, and 2.0 mg.ml−1) are fabricated and characterised for optimised photovoltaic performance. Consequently, the use of GO as HTM improved the quality of perovskite film by providing perovskite crystals with larger grain size and fewer pinholes. The power conversion efficiency (PCE) of 10.01% was obtained with GO dispersion concentration of 1.0 mg.ml−1, which was significantly higher than a similar device without HTM with a PCE of 8.32%. These results show that GO effectively serves as a promising HTM. Combined with the use of carbon as a replacement for metals as a back-contact electrode, this work demonstrates that the overall material cost for perovskite solar cells could be reduced while maintaining excellent photovoltaic performance.

Efficient interface engineering of N, N'-Dicyclohexylcarbodiimide for stable HTMs-free CsPbBr3 perovskite solar cells with 10.16%-efficiency

Optimized crystallization and defect passivation with Yttrium (III) doped MAPbBr3 film for highly efficient and stable hole-transport-layer-free carbon-based perovskite solar cells

Carbon-based perovskite solar cells (C-PSCs) hold great prospects for commercialization due to their lower manufacturing cost and better stability when compared with metal electrode perovskite. Nevertheless, their power conversion efficiency (PCE) is lower than those of metal-based perovskite solar cells because of the inadequate interface contact between the carbon electrode and the perovskite layer. In this study, the hole transport layer (HTL)-free carbon-based perovskite configuration is utilized to further reduce the cost, and the methylammonium chloride (MACl) additive is introduced to passivate the defects of the perovskite and enhance the interface contact performance. The results indicate that the MACl additive can improve the crystal quality of the perovskite film, reduce the density of defect states, fill the vacancies of the iodide ion, and inhibit the formation of the δ-phase. The optimized C-PSC exhibits an increased carrier lifetime, resulting in improved stability and PCE, with a champion efficiency of 18.04%. Additionally, the device demonstrates ultrahigh photoelectrical stability during continuous light illumination. The unpackaged device with the MACl additive retained 80% of its initial PCE after being operated for 1000 h under double 85 conditions (i.e., at 85 relative humidity (RH) and 85 °C). This work provides an extremely effective strategy for optimizing the interface contact of carbon-based perovskites and preventing the formation of the δ-phase, thereby leading to more efficient and stable optoelectronic devices.

Enhanced hole extraction by NiO nanoparticles in carbon-based perovskite solar cells

The paper presents design and implementing considerations for an agent-based environment monitoring and control system dedicated to a radiopharmaceuticals production line. This system is distributed on two layers: a centralized one, responsible for updating the status of the facility’s parameters and the global control strategy for cascade room parameters, and a distributed one that applies the global strategy to local environment control units—Heat Ventilation and Air Conditioning units (HVAC). The paper describes the environment parameters and defines the HVAC process models. The facility environment control system is developed in holonic approach, with three basic holons and one expertize holon. An implementing solution and integration of the environment control system with the radiopharmaceutical production management system is described. Experimental results and conclusions are finally presented.

Perovskite solar cells that use carbon (C) as a replacement of the typical metal electrodes, which are most commonly employed, have received growing interest over the past years, owing to their low cost, ease of fabrication and high stability under ambient conditions. Even though Power Conversion Efficiencies (PCEs) have increased over the years, there is still room for improvement, in order to compete with metal-based devices, which exceed 25% efficiency. With the scope of increasing the PCE of Carbon based Perovskite Solar Cells (C-PSCs), in this work we have employed a series of ammonium iodides (ammonium iodide, ethylammonium iodide, tetrabutyl ammonium iodide, phenethylammonium iodide and 5-ammonium valeric acid iodide) as additives in the multiple cation-mixed halide perovskite precursor solution. This has led to a significant increase in the PCE of the corresponding devices, by having a positive impact on the photocurrent values obtained, which exhibited an increase exceeding 20%, from 19.8 mA/cm2, for the reference perovskite, to 24 mA/cm2, for the additive-based perovskite. At the same time, the ammonium iodide salts were used in a post-treatment method. By passivating the defects, which provide charge recombination centers, an improved performance of the C-PSCs has been achieved, with enhanced FF values reaching 59%, which is a promising result for C-PSCs, and Voc values up to 850 mV. By combining the results of these parallel investigations, C-PSCs of the triple mesoscopic structure with a PCE exceeding 10% have been achieved, while the in-depth investigation of the effects of ammonium iodides in this PSC structure provide a fruitful insight towards the optimum exploitation of interface and bulk engineering, for high efficiency and stable C-PSCs, with a structure that is favorable for large area applications.

Enhanced charge extraction enabled by amide-functionalized carbon quantum dots modifier for efficient carbon-based perovskite solar cells

In the search for stable perovskite photovoltaic technology, carbon‐based perovskite solar cells (C‐PSCs) represent a valid, stable solution for near‐future commercialization. However, a complete understanding of the operational device stability calls for assessing the device robustness under thermal stress. Herein, the device response is monitored upon a prolonged thermal cycle aging (heating the device for 1 month up to 80 °C) on state‐of‐the‐art C‐PSCs, often neglected, mimicking outdoor conditions. Device characterization is combined with in‐house‐developed advanced modeling of the current–voltage characteristics of the C‐PSCs using an iterative fitting method based on the single‐diode equation to extrapolate series (RS) and shunt (RSH) resistances. Two temperature regimes are identified: Below 50 °C C‐PSCs are stable, and switching to 80 °C a slow device degradation takes place. This is associated with a net decrease of the device RSH, whereas the RS is unaltered, pointing to interface deterioration. Indeed, structural and optical analyses, by means of X‐ray diffraction and photoluminescence studies, reveal no degradation of the perovskite bulk, providing clear evidence that perovskite/contact interfaces are the bottlenecks for thermal‐induced degradation in C‐PSCs.

Carbon‐based perovskite solar cells (C‐PSCs) are inexpensive and stable, demonstrating great potential for commercial applications. However, the relatively low power conversion efficiency (PCE) stemmed from the poor conductivity of carbon electrodes and the energy level mismatch of the perovskite/carbon back interface are the key obstacles to further development of C‐PSCs. In this work, the electronic properties of a carbon electrode are regulated by designing a novel kind of B and N co‐doped carbon sphere (BN‐CS), resulting in a downshift of the Fermi level, which can minimize the energy level mismatch of the back interface. The optimized energy level alignment of the back interface accelerates the carrier separation, extraction, and transportation processes while effectively inhibiting charge recombination. Consequently, combined with an efficient buried passivation using aminomethylphosphonic acid, the PCE of the C‐PSCs is finally enhanced to 18.56%, much higher than that (15.16%) of the pristine C‐PSCs without any modification. Furthermore, the stability of the C‐PSCs is also enhanced using the synthesized BN‐CS with excellent hydrophobicity, and the PCE retention rate is up to 98.2% for the 30‐day stability test.

In recent decade, Perovskite Solar Cells (PSCs) have received considerable attention compared to other photovoltaic technologies. Despite the improvement of Power Conversion Efficiency (PCE) of PSCs, the chemical instability problem is still a matter of challenge. In this study, we have fabricated two kinds of PSCs based on gold and carbon electrodes with the optimal PCE of about 15 % and 10.2 %, respectively. We prepared a novel carbon electrode using carbon black nanopowder and natural graphite flaky powder for Hole Transport Material (HTM) free carbon-based PSC (C-PSC). Current density-voltage characteristics over time were measured to compare the stability of devices. Scanning Electron Microscope (SEM) and Energy-dispersive X-ray Spectroscopy (EDS) analyses were carried out to study applied materials, layer, and surface structures of the cells. The crystal structure of perovskite and its association with the stability of PSCs were analyzed using an obtained X-ray diffraction (XRD) pattern. As a result, the constructed HTM-free C-PSC demonstrated high stability against air, retaining up to 90 % of its optimal efficiency after 2000 h in the dark under ambient conditions (relative humidity of (50 ± 5); average room temperature of 25 °C) in comparison to constructed gold-based PSCs (Gold-PSC) which are not stable at times. The experimental results show that novel low-cost and low-temperature carbon electrode could represent a wider prospect of reaching better stability for PSCs in the future.

Perovskite solar cell (PSC) technology has achieved remarkable progress, with champion power conversion efficiencies (PCE) exceeding 26%. However, the long-term stability of PSCs remains a significant barrier to their widespread commercialization. Carbon-based PSCs (C-PSCs) have gained attention as a promising cost-effective and scalable production solution, replacing expensive metal electrodes and offering improved stability. Despite these advantages, C-PSCs face challenges in matching the performance of noble metal-based PSCs, particularly in terms of carrier extraction efficiency and reduced carrier recombination at the carbon/perovskite interface. The selection of hole transport materials (HTMs) is crucial for optimizing this interface, but comprehensive studies on HTM selection for C-PSCs are limited. This study systematically investigated three commonly used hole transport layers (HTLs): Spiro-OMeTAD, CuSCN, and PTAA. Our results show that Spiro-OMeTAD-based C-PSCs exhibit the best overall performance, achieving a PCE of 19.29%. CuSCN-based devices, while lower in efficiency (11.94% PCE), demonstrated superior stability, retaining approximately 60% of their initial performance after 500 hours under ambient conditions. PTAA-based devices achieved a PCE of 12.92% but exhibited significant degradation, maintaining only ∼35% of their original efficiency over the same duration. These findings highlight the importance of selecting HTLs that balance performance and stability and emphasize the need for further optimization to enhance the commercial viability of C-PSCs.