Stable Inverted Perovskite Solar Cells Research Articles

Simultaneous realization of bulk and interface regulation based on 2,4-diamino-6,7-diisopropylpteridine phosphate for efficient and stable inverted perovskite solar cells

A facile interface strategy based on 2,4-diamino-6,7-diisopropylpteridine phosphate is proposed to simultaneously regulate the bulk and interface recombination loss in the inverted perovskite solar cells.

Comprehensive interface engineering based on target anchoring agents for efficient and stable inverted perovskite solar cells

We propose a strategy that m-MTDATA into the PTAA/perovskite interface to enhance the wettability of PTAA and align energy levels of HTMs. PhABr is deposited onto perovskite surface to remove excessive residual PbI2 and compensates iodine vacancies.

Suppressing surface and interface recombination to afford efficient and stable inverted perovskite solar cells.

The top surface of the perovskite layer and the interface with the electron transporting layer play a key role in influencing the performance and operational stability of inverted perovskite solar cells (PSCs). A deficient or ineffective surface passivation strategy at the perovskite/electron transport layer interface can significantly impact the efficiency and scalability of PSCs. This study introduces phenyl dimethylammonium iodide (PDMAI2) as a passivation ligand that exhibits improved chemical and field-effect passivation at the perovskite/C60 interface. It was found that PDMAI2 not only passivates surface defects and suppresses recombination through robust coordination but also repels minority carriers and reduces contact-induced interface recombination. The approach leads to a twofold reduction in defect densities and photoluminescence quantum yield loss. This approach enabled high power conversion efficiencies (PCEs) of 25.3% for small-area (0.1 cm2) and 23.8% for large-area (1 cm2) inverted PSCs. Additionally, PDMAI2 passivation enabled PSCs to demonstrate steady operation at 65 °C for >1200 hours in an ambient environment.

Combining component screening, machine learning and molecular engineering for the design of high-performance inverted perovskite solar cells

To develop efficient and stable inverted perovskite solar cells, we describe an innovative strategy that combines component screening, machine learning and molecular engineering.

Interfacial engineering with trivalent cation for efficient and stable inverted inorganic perovskite solar cells

Metal halide inorganic perovskites with excellent thermal stability and ideal bandgaps are suitable for constructing inverted top subcells for tandem devices. However, facts such as defect-induced nonradiative recombination, interfacial energy...

Functional-Group-Induced Single Quantum Well Dion-Jacobson 2D Perovskite for Efficient and Stable Inverted Perovskite Solar Cells.

In two-dimensional/three-dimensional (2D/3D) perovskite heterostructure, randomly distributed multiple quantum wells (QW) 2D perovskites are frequently generated, which are detrimental to carrier transport and structural stability. Here, the high quality 2D/3D perovskite heterostructure is constructed by fabricating functional-group-induced single QW Dion-Jacobson (DJ) 2D perovskites. The utilization of ─OCH3 in the precursor solution facilitates the formation of colloidal particles with uniform size, resulting in the production of a pure 2D DJ perovskite with an n value of 3. This strategy facilitates the improvement of 3D structural stability and expedites carrier transport. The resultant devices accomplish a power conversion efficiency of 25.26% (certified 25.04%) and 23.56% at a larger area (1 cm2 ) with negligible hysteresis. The devices maintain >96% and >89% of their initial efficiency after continuous maximum power point tracking under simulated AM1.5 illumination for 1300h and under damp-heat conditions (85°C and 85% RH) for 1010h, respectively.

Managing Interfacial Charged Defects with Multiple Active Sited Macrocyclic Valinomycin for Efficient and Stable Inverted Perovskite Solar Cells.

The unavoidably positively and negatively charged defects at the interface between perovskite and electron transport layer (ETL) often lead to severe surface recombination and unfavorable energy level alignment in inverted perovskite solar cells (PerSCs). Inserting interlayers at this interface is an effective approach to eliminate charged defects. Herein, the macrocyclic molecule valinomycin (VM) with multiple active sites of ─C═O, ─NH, and ─O─ is employed as an interlayer at the perovskite/ETL contact to simultaneously eliminate positively and negatively charged defects. Combined with a series of theoretical calculations and experimental analyzes, it is demonstrated that the ─C═O and ─O─ groups in VM can immobilize the uncoordinated Pb2+ to manage the positively charged defect and the formation of N─H···I hydrogen bonding can recompense the formamidine vacancies to eliminate the negatively charged defect. In addition, the VM interlayer induces a favorable downshift band bending at the perovskite/ETL interface, facilitating charge separation and boosting charge transfer. Thanks to the reduced charged defects and favorable energy level alignment, the fabricated inverted PerSC delivers an outstanding power conversion efficiency of 24.06% with excellent long-term ambient and thermal stability. This work demonstrates that managing charged defects via multiple functional groups and simultaneously regulating energy level alignment is a reliable strategy to boost the performance of PerSCs.

The synergistic strategy of hexaazatrinaphthylene-cyanoindone-based electron transporting material enabling efficient and stable inverted perovskite solar cells

The synergistic strategy of hexaazatrinaphthylene-cyanoindone-based electron transporting material enabling efficient and stable inverted perovskite solar cells

Managing Excess Lead Iodide with Ordered Distribution and Reduced Photoactivity via Chelating Ligands for Stable Inverted Perovskite Solar Cells.

Excess lead iodide (PbI2) aggregates distributed in perovskite photoreactive absorbers will perturb carrier collection and become a key source of instability in PSCs. Herein, a multisite heterocyclic ligand of 2-mercaptonicotinic acid (2-MNA) is introduced as a chelating agent to manage excess PbI2 in inverted PSCs. The chelating coordination of 2-MNA to Pb2+ ions through the carbonyl, sulfhydryl, and pyridinyl groups enables a high-quality perovskite film with reduced PbI2 aggregates and the formation of an ordered distribution at grain boundaries. Moreover, the coordination of 2-MNA with the [PbX6]4- octahedron effectively inhibits the photodecomposition of PbI2-rich perovskites, thus preventing the generation of metallic lead (Pb0) and iodine (I2) species in response to environmental stimuli. As a result, the inverted PSC based on a 2-MNA modified triple cation perovskite photoactive layer achieves a PCE of 21.27% and a fill factor of 82.07%, accompanied by improved thermal and photostability.

π-Interactions suppression of buried interface defects for efficient and stable inverted perovskite solar cells

Poly(triarylamine) (PTAA) is commonly utilized as a hole transport layer due to suitable band alignment with perovskite layer, but its poor infiltration of perovskite precursors easily leads to buried interface defects. Here, we propose a molecular bridging strategy to bridge PTAA and perovskite layer by employing the special π-interactions molecule of 2, 4, 6-tris(4-aminophenyl)-s-triazine (TAPT). The amidogen of TAPT can produce H-π bond with the benzene ring in PTAA to make them bind tightly, thus fixing the fractures and reducing defect sites in PTAA, while the triazine ring of TAPT can interact with uncoordinated Pb2+ to form π-Pb2+ bond and passivate Pb2+ defects. In addition, the TAPT assists in achieving a pinhole-free buried interface, which enhances interfacial carrier transport and suppresses interfacial nonradiative recombination. Eventually, the device with TAPT achieves the champion efficiency of 24.57 %. The devices with TAPT have greatly improved operating and thermal stability, sustaining 89.7 % of the initial efficiency after 1500 h of maximum power point tracking and 91.9 % of the initial efficiency after 1065 h of 85 °C heat treatment. This approach focuses on the important role of the π-interactions at the buried interface to develop efficient and stable perovskite solar cells.

Functional layers in efficient and stable inverted tin-based perovskite solar cells

Functional layers in efficient and stable inverted tin-based perovskite solar cells

Interfacial Engineering of a PCBM/AZO Electron Transport Bilayer for Efficient and Stable Inverted Perovskite Solar Cells

AbstractThe reduced hysteresis index and low‐temperature processed fabrication of inverted p‐i‐n perovskite solar cells (PSC) have attracted substantial attraction for achieving higher photovoltaic performance through interfacial engineering. Despite having certain limitations, fullerene‐based electron transport layers have been used frequently utilized in mixed halide inverted perovskite solar cells. The energy level mismatch between PCBM and metal electrode creates a hindrance in efficient electron extraction and thus a limiting factor in attaining higher device performances. In this work, we report an efficient interlayer of aluminum‐doped zinc oxide (AZO) nanoparticles in‐between PCBM and the metal electrode to suppress interfacial recombination. The PCBM/AZO electron transport bilayer can effectively mitigate the imperfections of the PCBM layer alone. The PCBM/AZO electron transport bilayer with an optimal concentration of 2% Al dopant exhibited greatly improved power conversion efficiency (PCE) of 18.63%, VOC of 1.13 V, and FF of 73% with negligible hysteresis index of 0.04. Further, the optimal device exhibited remarkable stability by retaining 91% of the initial PCE after 200 hours confirming the suitable insertion of the AZO bilayer. The improved photovoltaic performance using PCBM/AZO bilayer can be attributed to higher electron transfer efficiency, suppressed interfacial recombination, and smooth surface morphology of AZO nanoparticles atop the PCBM layer.

Surface passivation by multifunctional carbon dots toward highly efficient and stable inverted perovskite solar cells

Interfacial imperfections between the perovskite layer and the electron transport layer (ETL) in perovskite solar cells (PSCs) can lead to performance loss and negatively influence long-term operational stability. Here, we introduce an interface engineering method to modify the interface between perovskite and ETL by using multifunctional carbon dots (CDs). C = O in the CDs can chelate with the uncoordinated Pb2+ in the perovskite material, inhibit interfacial recombination, and enhance the performance and stability of device. In addition, –OH in CDs forms hydrogen bonds with I− and organic cation in perovskite, inhibiting light-induced I2 release and organic cation volatilization, causing irreversible degradation of perovskite films, thereby enhancing the long-term operational stability of PSCs. Consequently, we achieve the champion inverted device with an efficiency of 24.02%. The CDs-treated PSCs exhibit high operational stability, and the maximum power point tracking only attenuates by 12.5% after 1000 h. Interfacial modification engineering supported by multifunctional quantum dots can accelerate the road to stable PSCs.

Pre‐buried Interface Strategy for Stable Inverted Perovskite Solar Cells Based on Ordered Nucleation Crystallization

AbstractThe buried interface has important effect on carrier extraction and nonradiative recombination of perovksite solar cells (PSCs). Herein, to inactivate the buried interfacial defects of perovskite and boost the crystallization quality of perovskite film, 3‐amino‐1‐adamantanol (AAD) serves as a pre‐buried interface modifier on nickel oxide (NiOx) surface to regulate the nucleation and crystallization process of perovskite precursor. The amino and hydroxyl groups in AAD molecule can synchronously coordinate with nickel ion (Ni3+) in NiOx and lead ion in perovskite, respectively. The dual action favors the ordered arrangement of AAD molecules between NiOx and perovskite, which not only enhances hole extraction in hole transport layer, but also provides active sites for homogeneous nucleation. Furthermore, AAD modifier blocks the unfavorable reaction between Ni3+ and perovskite, and effectively passivates the buried interfacial defects. The optimal inverted PSCs achieve a champion power conversion efficiency of 22.21% with negligible hysteresis, favorable thermal, optical, and long‐term stability. Thus, this strategy of modulating perovskite nucleation and crystallization by pre‐buried modifier is feasible for achieving efficient and stable inverted perovskite solar cells.

Constructing Heterostructure through Bidentate Coordination toward Operationally Stable Inverted Perovskite Solar Cells

It has been reported that one of the influencing factors leading to stability issues in iodine‐containing perovskite solar cells is the iodine loss from the perovskite layer. Herein, bidentate coordination is used with undercoordinated I− of the perovskite surface to construct the stable perovskite‐based heterostructure. This strong halogen bonding effectively inhibits interfacial migration of I− into functional layers such as C60 and Ag. Moreover, passivation of the undercoordinated I− suppresses the release of I2 and further delays the formation of voids at the perovskite surface. The resulting inverted perovskite solar cell exhibits a power conversion efficiency of 22.59% and the unencapsulated device maintains 96.15% of its initial value after continuous operation for 500 h under illumination.

Engineering Amorphous-Crystallized Interface of ZrNx Barriers for Stable Inverted Perovskite Solar Cells.

It is challenging to achieve long-term stability of perovskite solar cells due to the corrosion and diffusion of metal electrodes. Integration of compact barriers into devices has been recognized as an effective strategy to protect the perovskite absorber and electrode. However, the difficulty is to construct a thin layer of a few nanometers that can delay ion migration and impede chemical reactions simultaneously, in which the delicate microstructure design of a stable material plays an important role. Herein, ZrNx barrier films with high amorphization are introduced in p-i-nperovskite solar cells. To quantify the amorphous-crystalline (a-c) density, pattern recognition techniques are employed. It is found the decreasing a-c interface in an amorphous film leads to dense atom arrangement and uniform distribution of chemical potential, which retards the interdiffusion at the interface between ions and metal atoms and protect the electrodes from corrosion. The resultant solar cells exhibit improved operational stability, which retains 88% of initial efficiency after continuous maximum power point tracking under 1-Sun illumination at room temperature (25 °C) for 1500 h.

Star-like, dopant-free, corannulene-cored hole transporting materials for efficient inverted perovskite solar cells

Hole transporting materials (HTMs), owing to their unique bottom position in inverted perovskite solar cells (PSCs), exert a considerable influence on the hole-transporting process and the morphology/performance of the perovskite layers. Considering the well-known interfacial problems associated with commonly-used NiOx and poly(triarylamine) HTMs in traditional inverted PSCs, there is an urgent need for exploring efficient HTMs exhibiting good film formability/processability and interfacial contact to meet the specific requirements of high-performance and stable inverted PSCs. Herein, we fabricated inverted PSCs involving two star-like, dopant-free, corannulene-cored HTMs with O-terminals (sym-penta(N, N-bis(4-methoxyphenyl)aniline)corannulene, namely Cor-OMePTPA) and S-terminals (sym-penta(N, N-bis(4-(methylthio)phenyl)aniline)corannulene, namely Cor-SMePTPA) for the first time. The Cor-SMePTPA HTM exhibited a stronger hole-transporting ability and a better interfacial chemical linkage when compared to the Cor-OMePTPA HTM. The device containing Cor-SMePTPA HTM delivered a power conversion efficiency of 21.70%, which was the highest among inverted PSCs based on methylthio (SMe)-terminated HTMs. Furthermore, comprehensive experimental and theoretical characterizations clearly showed that the core and outer terminals (O or S) affected the optoelectric and chemical properties of the HTMs as well as the photovoltaic performance and stability of the corresponding PSCs, highlighting the superiority of the design involving a corannulene core and SMe groups in HTMs for inverted PSCs. We believe that such dopant-free corannulene-cored HTMs can have considerable potential for realizing highly efficient and stable PSCs in the future.

Buried Interface Engineering Enables Efficient, Scalable, and Stable Inverted Perovskite Solar Cells

Poly[bis(4‐phenyl)(2,4,6‐trimethylphenyl)amine] (PTAA), as an extensively used hole transport material in inverted perovskite solar cells (PSCs), has given reason for concern due to its hydrophobicity for a long time. Herein, buried interface engineering is applied for the scalable deposition of perovskite films by introducing an amphiphilic molecule hexadecyltrimethylammonium chloride on the PTAA surface, which improves the interfacial wettability of the perovskite precursor solution on the organic hole transport layer (HTL), facilitates the nucleation and growth of perovskites, and reduces the nonradiative recombination at the perovskite/HTL interface. As a result, all photovoltaic parameters of the inverted PSCs are improved significantly. The champion devices demonstrate power conversion efficiencies (PCEs) of 22.04% and 20.47% with aperture areas of 0.148 and 1.0 cm2, respectively. Moreover, the encapsulated 1.0 cm2 device exhibits excellent stability and maintains over 70% of its initial PCE after 1200 h under continuous 1 sun illumination at 65 °C in a nitrogen environment.

A novel perylene diimide-based ionene polymer and its mixed cathode interlayer strategy for efficient and stable inverted perovskite solar cells

Inverted (p–i–n) perovskite solar cells (PerSCs) have attracted much attention owing to their low temperature processability, less hysteresis effect and easy integration as a subunit for the tandem device. The unsatisfactory interface contacts and energy level barrier between adjacent interlayers on the cathode side are one of the key challenges for the development of p–i–n PerSCs. Herein, perylene diimide-based (PDI) ionene polymer was synthesized and developed as a cathode interlayer (CIL) to enhance interface contact, reduce the energy level barrier and prevent the migration of I- ions. The compact PNPDI CIL with high conductivity and appropriate lowest unoccupied molecular orbital (LUMO) level, resulted in a high efficiency device (20.03%), which is higher than the control device with bathophenanthroline (Bphen) (19.48%). Bphen-based CIL shows better adjusting ability of the work function of cathode metal but exhibits poor film-forming property. So, the synergistic effect of 1 + 1 > 2 can be obtained by combining Bphen and PNPDI into one CIL. As expected, the device performance was further improved by using the mixed CIL of Bphen and PNPDI, and 21.46% power conversion efficiency (PCE) was achieved. What’s more, the compact and hydrophobic mixed CIL dramatically enhanced the resistance to I- ions and moisture, which led to much enhanced device stability.

Fast and Balanced Charge Transport Enabled by Solution‐Processed Metal Oxide Layers for Efficient and Stable Inverted Perovskite Solar Cells

Metal oxide charge transport materials are preferable for realizing long‐term stable and potentially low‐cost perovskite solar cells (PSCs). However, due to some technical difficulties (e.g., intricate fabrication protocols, high‐temperature heating process, incompatible solvents, etc.), it is still challenging to achieve efficient and reliable all‐metal‐oxide‐based devices. Here, we developed efficient inverted PSCs (IPSCs) based on solution‐processed nickel oxide (NiOx) and tin oxide (SnO2) nanoparticles, working as hole and electron transport materials respectively, enabling a fast and balanced charge transfer for photogenerated charge carriers. Through further understanding and optimizing the perovskite/metal oxide interfaces, we have realized an outstanding power conversion efficiency (PCE) of 23.5% (the bandgap of the perovskite is 1.62 eV), which is the highest efficiency among IPSCs based on all‐metal‐oxide charge transport materials. Thanks to these stable metal oxides and improved interface properties, ambient stability (retaining 95% of initial PCE after 1 month), thermal stability (retaining 80% of initial PCE after 2 weeks) and light stability (retaining 90% of initial PCE after 1000 hours aging) of resultant devices are enhanced significantly. In addition, owing to the low‐temperature fabrication procedures of the entire device, we have obtained a PCE of over 21% for flexible IPSCs with enhanced operational stability.