Efficient Perovskite Solar Cells Research Articles

Engineering Spacer Conjugation for Efficient and Stable 2D/3D Perovskite Solar Cells and Modules

Incorporating 2D perovskite in 3D perovskite absorber holds great potential to improve the stability and efficiency of perovskite solar cells (PSCs). However, the bulky‐cation‐based 2D structures often exhibit poor charge transport and are prone to formation of charge‐extraction barrier that impedes efficient device operation. We address these issues by introducing aromatic spacers with enhanced molecular conjugation. Among our tested aromatic spacers, the pyrenylbutanamine (PyBA) spacer was shown to endow 2D perovskites with superior charge transport properties and efficient charge extraction from the bulk perovskite in 2D/3D PSCs, due to the highest degree of conjugation. As a result, we achieved a power conversion efficiency of up to 25.3% in a 0.16‐cm2 single cell and 21.0% in a 24.8‐cm2 module. Moreover, the incorporated PyBA substantially raised the resistance of 2D/3D PSCs against moisture and ion migration, resulting in enhanced environmental, thermal, and operational stability. Notably, the PyBA‐based devices retained over 90% of their initial efficiency after 2000 hours at 25 ℃ and 80% relative humidity, or 1000 hours at 85 ℃ and 85% humidity, or 3000 hours of operation under continuous 1‐Sun illumination at 40 ℃, showcasing their enhanced stability compared to previously reported 2D/3D PSCs.

Engineering Spacer Conjugation for Efficient and Stable 2D/3D Perovskite Solar Cells and Modules.

Incorporating 2D perovskite in 3D perovskite absorber holds great potential to improve the stability and efficiency of perovskite solar cells (PSCs). However, the bulky-cation-based 2D structures often exhibit poor charge transport and are prone to formation of charge-extraction barrier that impedes efficient device operation. We address these issues by introducing aromatic spacers with enhanced molecular conjugation. Among our tested aromatic spacers, the pyrenylbutanamine (PyBA) spacer was shown to endow 2D perovskites with superior charge transport properties and efficient charge extraction from the bulk perovskite in 2D/3D PSCs, due to the highest degree of conjugation. As a result, we achieved a power conversion efficiency of up to 25.3% in a 0.16-cm2 single cell and 21.0% in a 24.8-cm2 module. Moreover, the incorporated PyBA substantially raised the resistance of 2D/3D PSCs against moisture and ion migration, resulting in enhanced environmental, thermal, and operational stability. Notably, the PyBA-based devices retained over 90% of their initial efficiency after 2000 hours at 25 ℃ and 80% relative humidity, or 1000 hours at 85 ℃ and 85% humidity, or 3000 hours of operation under continuous 1-Sun illumination at 40 ℃, showcasing their enhanced stability compared to previously reported 2D/3D PSCs.

Using Post‐Treatment Additives for Crystal Modulation and Interface Passivation Enables the Fabrication of Efficient and Stable Perovskite Solar Cells in Air

AbstractHigh‐performance perovskite solar cells (PSCs) fabricated in ambient air are considered inevitable for low‐cost commercial manufacturing. However, passivating perovskite film defects and controlling the crystallization process are critical for achieving high performance in PSCs. This study proposes using the novel 2D material MBene in green antisolvent to simultaneously modulate the crystallization and passivation defects of perovskites. MBene facilitates the passivation of uncoordinated Pb2+ ions, thereby enhancing the formation energy of vacancies within the perovskite film and adjusting the energy level structure. Moreover, MBene increases nucleation sites for perovskite, significantly extending crystal growth and improving film crystallinity, thereby reducing non‐radiative recombination. Consequently, champion devices treated with MBene achieve a power conversion efficiency (PCE) of 24.22% when fabricated in air, and exhibit superior humidity and long‐term stability. Furthermore, PSCs with added MBene exhibit significant long‐term stability under various environmental conditions, including humidity and heat. The study results lay a foundation for the development of MBene materials in photovoltaics, revealing their mechanism as a new type of 2D material in perovskites, and providing new insights for industrially producing efficient and stable solar cells.

Three-Dimensional (3D) Fluoride Molecular Glue to Improve the SnO2/Perovskite Interface for Efficient Perovskite Solar Cells.

Aiming at numerous defects at SnO2/perovskite interface and lattice mismatch in perovskite solar cells (PSCs), we design a kind of three-dimensional (3D) molecular glue (KBF4-TFMSA), which is derived from strong intramolecular hydrogen bonding interaction between potassium tetrafluoroborate (KBF4) and trifluoromethane-sulfonamide (TFMSA). A remarkable efficiency of 25.8 % with negligible hysteresis and a stabilized power output of 25.0 % have been achieved, in addition, 24.57 % certified efficiency of 1 cm2 device is also obtained. Further investigation reveals that this KBF4-TFMSA can interact with oxygen vacancies and under-coordinated Sn(IV) from the SnO2, in the meantime, FA+ (NH2-C=NH2 +) and K+ cations can be well fixed by hydrogen bonding interaction between FA+ and BF4 -, and electrostatic attraction between sulfonyl oxygen and K+ ions, respectively. Thereby, FAPbI3 crystal grain sizes are increased, interfacial defects are significantly reduced while carrier extraction/ transportation is facilitated, leading to better cell performance and excellent stabilities. Non-encapsulated devices can maintain 91 % of their initial efficiency under maximum-power-point (MPP) tracking while continuous illumination (~100 mW cm-2) for 1000 h, and retain 91 % of the initial efficiency after 1000 h "double 60" damp-heat stability testing (60 °C and 60 %RH (RH, relatively humidity)).

Enhanced charge carrier transport and defects mitigation of passivation layer for efficient perovskite solar cells

Surface passivation has been developed as an effective strategy to reduce trap-state density and suppress non-radiation recombination process in perovskite solar cells. However, passivation agents usually own poor conductivity and hold negative impact on the charge carrier transport in device. Here, we report a binary and synergistical post-treatment method by blending 4-tert-butyl-benzylammonium iodide with phenylpropylammonium iodide and spin-coating on perovskite surface to form passivation layer. The binary and synergistical post-treated films show enhanced crystallinity and improved molecular packing as well as better energy band alignment, benefiting for the hole extraction and transfer. Moreover, the surface defects are further passivated compared with unary passivation. Based on the strategy, a record-certified quasi-steady power conversion efficiency of 26.0% perovskite solar cells is achieved. The devices could maintain 81% of initial efficiency after 450 h maximum power point tracking.

Efficient and stable perovskite solar cells based on multi-active sites 5-amino-1,3,4-thiadiazole-2-thiol modified interface

The highest certification efficiency of perovskite solar cells (PSCs) has reached 26.7 %. However, the high defect density on the surface of perovskite films prepared by low temperature solution method and the energy mismatch between the carrier transport layers and perovskite layer (PVK) greatly limit the performance improvement of PSCs. The introduction of passivating agent to modify the perovskite interface and grain boundary can reduce the defect density, coordinate the energy level effectively, and improve the efficiency and stability of devices. A Lewis base molecule 5-amino-1,3,4-thiadiazole-2-thiol (AMTD) with multiple active sites is introduced at the interface between PVK and hole transport layer (HTL). The electron-rich groups, such as = S, –S–, –NH2, –N on AMTD, passivate the positive electrical defects on the interface and grain boundary, and increase carrier transport efficiency. The interfacial energy level array is optimized to achieve more efficient charge transportation. In addition, the modified of AMTD has a significant protective effect on the perovskite, which inhibit the moisture erosion of in environment. Consequently, the AMTD-optimized device achieves a power conversion efficiency (PCE) of 24.13 %, compared to the efficiency of 21.62 % for pristine device. The stability of the devices is improved greatly.

Study on the enhancement of device performance by the action of carbonohydrazide at the buried bottom interface of inverted mesoporous perovskite solar cells

The interface of perovskite solar cells (PSCs) significantly influences their efficiency and stability. Researchers tend to pay more attention to the upper surface of the perovskite absorber layer and conduct relatively less research on the bottom buried interface, mainly because the bottom of the perovskite film is challenging to peel off, which increases the difficulty of the characterization of the observation and analysis. Defects at the bottom interface make it more challenging to optimize the treatment than the upper surface. For inverted PSCs, the interface located in direct contact between the light absorption layer of perovskite and the hole transport layer is the buried interface. The buried interface is the direct interface for transporting charge carriers of PSCs and is also the center of non-radiative compound enrichment. The defect density is higher than the defect density of perovskite film crystal. Due to the DMSO initially left in the commonly used perovskite precursor solution during the film formation process, evaporation during the annealing and crystallization process creates vacancy holes at the bottom of the perovskite layer film. These holes and crystal boundaries tend to produce many non-radiative recombinations. These holes are also the sites of photodecomposition, leading to reduced efficiency and stability in PSCs, ultimately impacting the overall performance of PSCs. The work adds an Al2O3 mesoporous layer on top of the hole transport layer (HTL), which reduces the direct contact area between PTAA and perovskite film. In the perovskite precursor solution, we incorporate a solid additive called Carbonohydrazide (CBH), this substance replaces some of the DMSO and fills in the voids at the bottom of the perovskite film that is left when the DMSO evaporates. This process helps to reduce non-radiative recombination and photodegradation caused by the voids at the bottom of the perovskite, leading to an improvement in the efficiency and stability of the cell. The optimization of the buried bottom interface has improved the cell’s average efficiency from 17.6 % to 19.7 %, an 11.9 % increase. The aperture area of the devices in this work is 0.048 cm2, and the photoelectric conversion efficiency of our device still reaches 80.64 % of the initial efficiency after 600 h of continuous heating in a glove box with a nitrogen atmosphere, maintaining a test temperature of 60 °C.

Molecularly tailored bifunctional nano-overlayers for efficient and stable inverted perovskite solar cells

Triple cation perovskite solar cells (PSCs) have made remarkable progress in power conversion efficiency (PCE), which is also related to the interface regulation layers between the active layer and electron transport layer (ETL). The ionic nature of the perovskite lattice has enabled approaches to passivate molecular defects through the interaction of functional groups. Herein, a passivator OXD-7 is introduced as a modified layer to passivate surface defects and accelerate electron transfer. It has been observed that OXD-7 can alleviate the micro-strain of the perovskite thin films through intermolecular bonding, which suppresses the iodide vacancy on the perovskite surface. Additionally, the OXD-7 reduces the surface energy of the perovskite films and inhibits the formation of δ-FAPbI3 on the surface of perovskite film. Consequently, the resulting devices demonstrate improved fill factor and device stability. Under optimal fabrication conditions, triple cation mixed perovskite solar cells with an inverted structure achieve a PCE of 23.83%.

Improved efficiency and stability of inverse perovskite solar cells via passivation cleaning

Amidst the global energy and environmental crisis, the quest for efficient solar energy utilization intensifies. Perovskite solar cells, with efficiencies over 26% and cost-effective production, are at the forefront of research. Yet, their stability remains a barrier to industrial application. This study introduces innovative strategies to enhance the stability of inverted perovskite solar cells. By bulk and surface passivation, defect density is reduced, followed by a "passivation cleaning" using Apacl amino acid salt and isopropyl alcohol to refine film surface quality. Employing X-ray diffraction (XRD), scanning electron microscope (SEM), and atomic force microscopy (AFM), we confirmed that this process effectively neutralizes surface defects and curbs non-radiative recombination, achieving 22.6% efficiency for perovskite solar cells with the composition Cs0.15FA0.85PbI3. Crucially, the stability of treated cells in long-term tests has been markedly enhanced, laying groundwork for industrial viability.

Exploring the impact of halide composition on stability and power conversion efficiency in all-inorganic perovskite solar cells

Exploring the impact of halide composition on stability and power conversion efficiency in all-inorganic perovskite solar cells

Lead iodide secondary growth and π-π stack regulation for sequential perovskite solar cells with 23.62% efficiency

The sequential deposited perovskite solar cells (PSCs) have received widespread attention due to its application potential in large-scale perovskite module and perovskite/silicon tandem solar cells. However, insufficient reaction between organic ammonium salts and PbI2 leads to residual PbI2 and low crystallinity of perovskite films, and the fragile Pb-I bonds easily creates iodine loss and reduces the stability of PbI6 framework. In this work, the 4-fluorobenzylamine (FBA) with C = O and –NH2 is employed in PbI2 precursor solution to regulate the secondary growth process of PbI2 film. Due to the low Gibbs free energy and high crystallinity of porous PbI2 film, sufficient reaction between organic ammonium salts and PbI2 is promoted, which results in large-grain, low-defect perovskite films. At the same time, through hydrogen bonding and π-π stacking interactions, the stability of the PbI6 skeleton is effectively improved, significantly suppressing non-radiative recombination and reducing defect state density. Finally, this strategy increases the power conversion efficiency (PCE) of PSCs from 22.06 % to 23.62 %, and the target PSCs maintain 96 % of their initial PCE after being placed in nitrogen for 1300 h.

Synergetic effect of non-invasive posttreatment agents enables highly efficient and stable all-inorganic Sn-Pb perovskite solar cells

All-inorganic tin–lead perovskites present a promising avenue for achieving an ideal bandgap, approaching the Shockley-Queisser limit, while circumventing the use of volatile organic cations. However, challenges such as relatively low power conversion efficiency (PCE) and rapid degradation dynamics—stemming from complex film crystallization mechanisms and Sn oxidation—hinder their advancement. In this study, we employed sequential interface engineering on the CsPb0.6Sn0.4I3 system, utilizing non-invasive carbazole propylamine bromide and ethylenediamine diiodide as post-treatment agents. This approach significantly enhances both the bulk structure and surface morphology, thereby promoting charge transport, suppressing non-radiative recombination, and improving structural stability. The champion device achieved a PCE of 16.62 % and demonstrated over 2200 h of T80 stability in dry N2. Remarkably, stability in high-humidity environments was validated through device aging tests and in situ GIWAXS analysis. These results underscore the substantial potential of sub-1.4 eV bandgap all-inorganic Sn-Pb perovskite solar cells.

Highly Efficient Wide Bandgap Perovskite Solar Cells With Tunneling Junction by Self-Assembled 2D Dielectric Layer.

Reducing non-radiative recombination and addressing band alignment mismatches at interfaces remain major challenges in achieving high-performance wide-bandgap perovskite solar cells. This study proposes the self-organization of a thin two-dimensional (2D) perovskite BA2PbBr4 layer beneath a wide-bandgap three-dimensional (3D) perovskite Cs0.17FA0.83Pb(I0.6Br0.4)3, forming a 2D/3D bilayer structure on a tin oxide (SnO2) layer. This process is driven by interactions between the oxygen vacancies on the SnO2 surface and hydrogen atoms of the n-butylammonium cation, aiding the self-assembly of the BA2PbBr4 2D layer. The 2D perovskite acts as a tunneling layer between SnO2 and the 3D perovskite, neutralizing the energy level mismatch and reducing non-radiative recombination. This results in high power conversion efficiencies of 21.54% and 19.16% for wide-bandgap perovskite solar cells with bandgaps of 1.7 and 1.8 eV, with open-circuit voltages over 1.3 V under 1-Sun illumination. Furthermore, an impressive efficiency of over 43% is achieved under indoor conditions, specifically under 200 lux white light-emitting diode light, yielding an output voltage exceeding 1 V. The device also demonstrates enhanced stability, lasting up to 1,200 hours.

Efficient and stable all-inorganic perovskite solar cells prepared with ABX3-like precursors

Despite the fact that inorganic perovskites with supreme thermal stability are attractive photo-absorbers for emerging photovoltaic cells, intrinsic phase-instable issues pose challenges for obtaining satisfactory photovoltaic efficiencies and long-term device stability. Herein, we demonstrate an all-solution approach based on a series of perovskite-like products (PLP), namely NH4PbX3 (X = halogen) as the reactant for preparing inorganic perovskites featuring a heterojunction-resembling structure (HRS) and high material robustness. The creation of HRS is enabled by a self-migration and assembly process facilitated by the volatile characteristics of PLPs, as affirmed by joint experiential and theoretical investigations. We highlight that the particular structure of HRS is a key to the boost in material robustness, which translates to long-term device stability. Engaging compositional engineering on the PLPs allows us to regulate the energetics of surface components within the HRS, leading to gradient energy alignments to promote carrier transport and extraction in the device. Based on an optimized PLP (NH4PbCl2.8Br0.2) to form the HRS, the resultant solar cell yields a power conversion efficiency (PCE) exceeding 20 %, showing excellent operational stability under illumination (the efficiency remains over 95 % of its initial value after 1000 hours of continuous illumination). The described PLP-based approach can be readily applied to a range of inorganic perovskite materials for receiving gains in photovoltaic performance.

Small molecule of aminoacetonitrile hydrochloride prompting large improvement in the performance of perovskite solar cells

Perovskite solar cells (PSCs) continuously update their best research efficiency records, currently has exceeded 26 %. However, the industrialization of PSCs still faces the issues of stability and performance improvement, and interface defects are notorious negative factors. Herein, a small molecule aminoacetonitrile hydrochloride (AAN) as multi-functional additive is introduced into the interface of tin oxide (SnO2)/perovskite. The cyano group (CN) on AAN can coordinate with Pb2+ on perovskite; Cl− can occupy halide vacancy in perovskite and oxygen vacancy on SnO2, and NH3+ can form hydrogen bonding with iodide ions in perovskite. It is verified that crystal growth quality is improved, trap-state density is reduced, energetic alignment is adjusted, charge transfer is ameliorated, and carrier recombination is alleviated. Therefore, the AAN-modified PSC achieves a maximum power conversion efficiency of 24.52 % with a high open-circuit voltage of 1.18 V and satisfactory stability, compared to the unmodified device efficiency of 21.24 %, demonstrating a significant impact of the multi-functional small molecule of AAN in highly efficient and stable PSCs.

NiO/MWCNT incorporated methyl ammonium lead iodide for an efficient perovskite solar cells

The perovskite solar cells (PSCs) reveal the impressive performance due to the extraordinary characteristic features of perovskite material and its fabrication methods. The complex deposition process and hygroscopic nature of hole transport materials are biggest obstacles for attaining high power conversion efficiency (PCE) with long term stability in PSC. In this study, NiO/MWCNT nanocomposites have been synthesized by hydrothermal method and are incorporated in CH3NH3PbI3 to increase the performance of PSCs with stability. The incorporation has been carried out to improve the properties of CH3NH3PbI3 such as formation of large grain size/grain boundaries, reduce the defects that enhance the charge generation/collection and reduction in recombination. The fabricated PSCs with NiO/MWCNT revealed a PCE of 14.93 % with moderate hysteresis, which is significantly higher PCE than that of pristine PSC. The enhanced recombination resistance was observed by electrochemical impedance spectroscopy, which evinces the remarkable PCE of NiO/MWCNT incorporated PSC. The strong PL quenching and red shift of PL spectrum confirms the low recombination and larger grains in the NiO/MWCNT-CH3NH3PbI3 layer. Moreover, the NiO/MWCNT incorporated PSC retains 94 % of its initial PCE after 600 h of aging under atmospheric condition whereas the PCE of pristine PSC shows 87 % of its initial PCE value. The carbon back electrode also supports to lift up PCE and stability of PSCs.

Unveiling full-dimensional distribution of trap states toward highly efficient perovskite photovoltaics

To gain a deep understanding and address key issues in perovskite photovoltaics, such as power conversion efficiency (PCE) and long-term stability, defect passivation and analysis of the device performance are required. Here, we proposed a non-contact characterization technique named scanning photocurrent measurement system (SPMS) for device surface detection, having conducted signal analysis and method adjustments based on perovskite photovoltaic devices. This technique enables the monitoring of minority carriers in the device, allowing for the investigation of carrier behavior based on photocurrent signals. By integrating SPMS with thermal conductance spectroscopy (TAS) and drive-level capacitance profiling (DLCP), we further simulated a spatial three-dimensional (3D) distribution of trap states in the device and analyzed the distribution of trap states matched with energy space. Through extensive case studies, we have validated the universality and accuracy of this method. The integration of trap state characterization techniques provides strong support for targeted defect passivation and performance evaluation of perovskite photovoltaic devices, yielding a highly efficient perovskite solar cell with PCE as high as 25.74%.

Machine learning-assisted SCAPS device simulation for photovoltaic parameters prediction of [formula omitted] perovskite solar cells

Perovskite solar cells (PSCs) have garnered significant research attention because of their remarkable surge in power conversion efficiency (PCE) surpassing 26% within a short timeframe. However, the widespread adoption of these highly efficient PSCs is hampered by the inherent toxicity associated with lead (Pb)-based perovskites, which currently dominate the field. Researchers have explored alternative cations like Ge2+ and Sn2+ Owing to their identical oxidation states to Pb2+, paving the way for lead-free PSC development. By examining the critical factors influencing CsSnI3 thin film solar cells’ performance as well as their interdependencies, this work seeks to improve the efficiency of these devices. To do so, machine learning algorithms (ML) are employed to figure out the critical factors influencing the completion of CsSnI3 solar cells. A new dataset of 7870 data points is generated through simulations with SCAPS-1D to effectively depict the perovskite solar cell. Five ML regression algorithms are thereafter utilized to predict the photovoltaic parameters of solar cells, such as the fill factor (FF), open circuit voltage (VOC), short circuit current (JSC), and PCE. The study shows that random forest (RF) and decision tree (DT) are the best performing algorithms, among which DT produces high accuracy and low error for predicting the PCE with a coefficient of determination R2 of 0.99, Pearson’s coefficient (Rvalue) of 0.99, Spearman’s correlation coefficient (ρ) of 0.99 and root mean square error of 0.08 on the testing set. Finally, this study offers valuable guidance for further experiment optimization by shedding light on the optimal device dimensions and essential components.

Modelling and Numerical Evaluation of Photovoltaic Parameters of a Highly Efficient Perovskite Solar Cell Based on Methylammonium Tin Iodide.

Designing a high performance solar cell structure requires the understanding of material innovation, device engineering, charge behavior, operation characteristics and efficient photoconversion of light to generate electricity. This study offers a detailed numerical evaluation of the device physics in a highly efficient methylammonium-based perovskite solar cell (PSC) of the configuration, FTO/WO3/CH₃NH₃SnI₃/GO/Fe. Utilizing the SCAPS-1D device simulator, an impressive open-circuit voltage (Voc) of 1.3184 V, short-circuit current density (Jsc) of 35.10 mA/cm², Fill factor (FF) of 78.38%, and power conversion efficiency (PCE) of 36.24% were achieved. The model cell exhibits a robust photon capture of 100% quantum efficiency between 360 and 750 nm. The study also presents temperature-dependent band alignment diagram which posted a built-in potential (Vbi) of 0.62 eV. The Vbi at 400 K was found to be 0.58 eV indicating that the model cell exhibits a decent temperature tolerance, and can retain approximately 93% of its power at 400 K. Through Mott-Schottky capacitance analysis, deeper insights into the space-charge region are inferred, while recombination-generation investigations emphasize the significance of electronic properties in optimizing device performance. This paper, therefore, lays the foundation for future studies, offering clear pathways for device optimization and identifying key areas that require further investigation.

Pyridalthiadiazole-Based Molecular Chromophores for Defect Passivation Enables High-Performance Perovskite Solar Cells.

Passivation of defects at the surface and grain boundaries of perovskite films has become one of the most important strategies to suppress nonradiative recombination and improve optoelectronic performance of perovskite solar cells (PSCs). In this work, two conjugated molecules, abbreviated as CPT and SiPT, are designed and synthesized as the passivator to enhance both efficiency and stability of PSCs. The CPT and SiPT contain pyridalthiadiazole (PT) units, which can coordinate with undercoordinated Pb2+ at the surface and grain boundaries to passivate the defects in perovskite films. In addition, with the incorporation of CPT, the crystallized perovskite films exhibit more uniform grain size and smoother surface morphology relative to the control ones. The efficient passivation by CPT also results in better charge extraction and less carrier recombination in PSCs. Consequently, the CPT-passivated PSCs yield the highest power conversion efficiency (PCE) of 23.14% together with better storage stability under ambient conditions, which is enhanced relative to the control devices with a PCE of 22.14%. Meanwhile, the SiPT-passivated PSCs also show a slightly enhanced performance with a PCE of 22.43%. Our findings provide a new idea for the future design of functional passivating molecules towards high-performance PSCs.