JIALINGBO

An environmental-friendly PBAT polymer is adopted to implant the perovskite film with an anti-solvent method, which can passivate the uncoordinated Pb²⁺ and neutral iodine defects of perovskite material and markedly improve device efficiency and operational stability. More importantly, the polymer network can prevent nearly 98% of Pb²⁺ from leaking by directly immersing the polymer-coated perovskite film in water.

Abstract

Although perovskite solar cells (PSCs) are on the road to industrialization, the operational stability under high efficiency still needs to be improved, and the water solubility of lead ions (Pb²⁺) will cause environmental pollution problems. Herein, it is successfully implanted an environment-friendly (biodegradability) poly(butylene adipate-coterephthalate) polymer (PBAT) into the perovskite film, which can passivate the uncoordinated Pb²⁺ and neutral iodine defects of the perovskite material because of the adequate carbonyl groups and benzene rings in PBAT polymer, thereby regulating the crystallization of perovskite film with lower trap density, inhibiting the nonradiative recombination and improving charge carrier transport. As a result, the polymer-incorporated inverted PSCs achieve optimal conversion efficiencies of 22.07% (0.1 cm²) and 20.31% (1 cm²). Meanwhile, the incorporated device, after being encapsulated, exhibits a prominent improvement in operational stability of high-efficiency device under maximum power point tracking and continuous one sunlight illumination, maintaining the initial efficiency of 80% for 3249 h. More importantly, the polymer network can protect Pb²⁺ from being dissolved by water and prevent nearly 98% of Pb²⁺ from leaking by directly immersing the polymer-coated perovskite film in water. Environmental-friendly molecules provide new hope for solving lead poisoning and improving device operational stability under high efficiency.

Polyacrylonitrile which has C≡N groups was introduced to passivate the uncoordinated lead cations in perovskite films. The coordination of C≡N with the lead cation was much stronger than that of the normally used C=O group. It could also reduce the I/Pb ratio at the film surface. The device efficiency was improved from 21.58 % to 23.71 %, with the open-circuit voltage enhanced from 1.12 V to 1.23 V.

Abstract

In solution-processed organic–inorganic halide perovskite films, halide-anion related defects including halide vacancies and interstitial defects can easily form at the surfaces and grain boundaries. The uncoordinated lead cations produce defect levels within the band gap, and the excess iodides disturb the interfacial carrier transport. Thus these defects lead to severe nonradiative recombination, hysteresis, and large energy loss in the device. Herein, polyacrylonitrile (PAN) was introduced to passivate the uncoordinated lead cations in the perovskite films. The coordinating ability of cyano group was found to be stronger than that of the normally used carbonyl groups, and the strong coordination could reduce the I/Pb ratio at the film surface. With the PAN perovskite film, the device efficiency improved from 21.58 % to 23.71 % and the open-circuit voltage from 1.12 V to 1.23 V, the ion migration activation energy increased, and operational stability improved.

Publication date: 18 May 2022

Source: Joule, Volume 6, Issue 5

Author(s): Minhuan Wang, Yepin Zhao, Xiaoqing Jiang, Yanfeng Yin, Ilhan Yavuz, Pengchen Zhu, Anni Zhang, Gill Sang Han, Hyun Suk Jung, Yifan Zhou, Wenxin Yang, Jiming Bian, Shengye Jin, Jin-Wook Lee, Yang Yang

A two-in-one dyad additive combining phosphonate and phosphine oxide groups for efficient perovskite light-emitting diodes (PeLEDs) is demonstrated. Owing to its dual roles of passivating defects and enhancing carrier radiative recombination, quasi-two-dimensional green PeLEDs with maximum external quantum efficiency of 25.1 % is obtained.

Abstract

Additives play a critical role for efficient perovskite light-emitting diodes (PeLEDs). Here, we report a novel phosphonate/phosphine oxide dyad molecular additive (PE-TPPO), with unique dual roles of passivating defects and enhancing carrier radiative recombination, to boost the device efficiency of metal–halide perovskites. In addition to the defect passivation effect of the phosphine oxide group to enhance the photoluminescence intensity and homogeneity of perovskite film, the phosphonate group with strong electron affinity can capture the injected electrons to increase local carrier concentration and accelerate the carrier radiative recombination in the electroluminescence process. Owing to their synergistic enhancement on device efficiency, quasi-two-dimensional green PeLEDs modified by this dyad additive exhibit a maximum external quantum efficiency, current efficiency, and power efficiency of 25.1 %, 100.5 cd A⁻¹, and 98.7 lm W⁻¹, respectively, which are among the reported state-of-the-art efficiencies.

It is demonstrated that high-quality CsPbI₂Br perovskite films could be prepared by using 2D non-layered materials as additives, such as In₂S₃ nanoflakes (Nano-In₂S₃) with well-matched lattices and unsaturated dangling bonds on the surface. As a result, the organic-free perovskite solar cells with inverted configuration exhibit improved device performance along with excellent stability.

Organic-free perovskite solar cells (PSCs) have been of rising interest due to their remarkable resistance toward long-term thermal stress. Nevertheless, the inorganic perovskite films usually suffer from poor crystallization and high-density defects in bulk and near/at the interfaces, which leads to significant charge recombination loss and hence inferior device performance. Herein, it is demonstrated that high-quality CsPbI₂Br perovskite films could be prepared by using 2D non-layered materials as additives, such as In₂S₃ nanoflakes (Nano-In₂S₃) with well-matched lattices and unsaturated dangling bonds on the surface. In addition, it is found that the introduction of Nano-In₂S₃ results in not only defect passivation but also remarkable quasi-Fermi level splitting across the perovskite film due to its gradient doping behavior, thereby enhancing the built-in electric field in the inverted PSCs. As a result, the optimal devices based on Nano-In₂S₃:CsPbI₂Br absorber and all-inorganic interfacial layers deliver a champion power conversion efficiency of 15.17% along with excellent ambient and thermal stabilities, superior to those of the pristine devices and comparable to the best organic-free PSCs. A novel strategy for highly efficient and stable organic-free photovoltaics by using 2D non-layered materials as multifunctional additives is demonstrated.

L-4-fluorophenylalanine (FPA) is introduced in a MAPbI₃ perovskite film as a multifunctional molecular additive achieving comprehensive defect passivation, surface hydrophobicity, and crystallization control. The FPA-modified inverted perovskite solar cell shows a champion efficiency of 21.28% with negligible hysteresis and maintains outstanding long-term stability.

The harmful defects accumulated at surfaces and grain boundaries (GBs) limit the performance and stability of perovskite solar cells (PSCs), which results from the poor crystallization and ion migration. Here, a multifunctional molecular additive L-4-fluorophenylalanine (FPA) is explored for highly efficient and stable inverted PSCs. The multifunction is realized through comprehensive defect passivation, surface hydrophobicity, and crystallization control with the multitude groups, such as the amino and carbonyl groups for passivating the unsaturated lead defects at GBs, and the benzene ring for electron-deficient iodine defects, and the fluorine group for the improvement of crystallization and the inhibition of ions migration. The resulting inverted device shows a champion power conversion efficiency of 21.28% with negligible hysteresis. The unencapsulated FPA-modified devices maintain nearly 90% of the initial performance after high-temperature (85 °C) thermal accelerated aging for 500 h and 85% after aging for 4000 h under ambient conditions, and about 90% of the original efficiency after being maximum power point tracked for 1000 h under continuous illumination. This study provides a multipronged strategy to the future design of PSCs with higher efficiency and enhanced stability.

Herein, a unique SnO₂ layer to protect the underlaying layers from damage of the sputtered transparent electrode is developed. Moreover, a high-near-infrared transparent perovskite solar cell using cerium-doped indium oxide is prepared, achieving a record power conversion efficiency (PCE) of 17.23%. As a result, a four-terminal perovskite/silicon tandem solar cell with a PCE of 26.14% is obtained.

Two issues need to be resolved when fabricating p–i–n semitransparent perovskite solar cells (ST-PVSCs) for four-terminal (4 T) perovskite/silicon tandem solar cells: 1) damage to the underlying absorber (MAPbI₃), electron transporting layer ([6,6]-phenyl-C₆₁-butyric acid methyl ester, PCBM), and work function (WF) modifier (polyethylenimine, PEI), resulting from the harsh sputtering conditions for the transparent electrodes (TEs) and 2) low average near-infrared transmittance (ANT) of TEs. Herein, a unique SnO₂ layer to protect the MAPbI₃ and PCBM layers is developed and functions as a WF modifier for a new TE (cerium-doped indium oxide, ICO), which exhibits an excellent ANT of 86.7% in the range of 800−1200 nm. Moreover, a MAPbI₃-based p–i–n ST-PVSC is prepared, achieving an excellent power conversion efficiency (PCE) of 17.23%. When it is placed over the Si solar cell, a 4 T tandem solar cell with a PCE of 26.14% is obtained.

Perovskite Solar Cells

In article number 2100891, Yu-Ching Huang, Wei-Fang Su, and co-workers developed a highly efficient semi-transparent perovskite solar cell (ST-PVSC) using a unique electron transport layer of ligand modified SnO₂ on a fullerene derivative and near-infrared transparent conducting electrode of cerium doped SnO₂. The high efficiency 4-terminal perovskite/silicon tandem solar cells are obtained by employing this new ST-PVSC.

Herein, X-ray photoelectron spectroscopy on n–i–p and p–i–n architecture is used to study the interface at the perovskite and hole transporting layer. The band bending at the perovskite/hole transporting layer in both the architectures is found to be 0.5 eV. In n–i–p, the band bending is in the Spiro while in p–i–n is in the perovskite layer.

Interfaces between hybrid perovskite absorber and its adjacent charge-transporting layers are of high importance for solar cells performance. Understanding their chemical and electronic properties is a key step in designing efficient and stable perovskite solar cells. In this work, the tapered cross-section photoemission spectroscopy (TCS-PES) method is used to study the methylammonium lead iodide (CH₃NH₃PbI₃) (MAPI)-based solar cells in two configurations, that is, in an inverted p–i–n and in a classical n–i–p architecture. It is revealed in the results that the MAPI film deposited once on the n-type TiO₂ and once on the p-type NiO _x substrates is neither an intrinsic semiconductor nor adapts to the dopant nature of the substrate underneath, but it is heavily n-type doped on both substrates. In addition to that, the TCS-PES results identify that the band bending between the MAPI film and the hole transporting layer (HTL) layer depends on the perovskite solar cells architecture. In particular, a band bending on the HTL side in the n–i–p and at the MAPI in the p–i–n architecture is found. The flat band of NiO _x at the NiO _x /MAPI interface can be explained by the Fermi level pinning of the NiO _x at the interface.

All the reported perovskite modules have a combination of different deposition methods for the perovskites and the charge-transport layers, which limits high-throughput module production. A combination of any amine molecules and 4-(2,3-dihydro-1,3-dimethyl-1H-benzimidazol-2-yl)-N,N-dimethylbenzenamine (N-DMBI) added in phenyl-C₆₁-butyric acid methyl ester (PCBM) allows the electrically conductive PCBM layers to conformally cover the perovskites and achieve high-efficiency PSCs and modules with all-bladed perovskite and charge-transport layers.

Abstract

Perovskite solar cells (PSCs) are promising to reduce the cost of photovoltaic system due to their low-cost raw materials and high-throughput solution process; however, fabrication of all the active layers in perovskite modules using a scalable solution process has not yet been demonstrated. Herein, the fabrication of highly efficient PSCs and modules in ambient conditions is reported, with all layers bladed except the metal electrode, by blading a 36 ± 9 nm-thick electron-transport layer (ETL) on perovskite films with a roughness of ≈80 nm. A combination of additives in phenyl-C₆₁-butyric acid methyl ester (PCBM) allows the PCBM to conformally cover the perovskites and still have a good electrical conductivity. Amine-functionalized molecules are added to enhance both the dispersity of PCBM and the affinity to perovskites. A PCBM dopant of 4-(2,3-dihydro-1,3-dimethyl-1H-benzimidazol-2-yl)-N,N-dimethylbenzenamine (N-DMBI) recovers the conductivity loss induced by the small amine molecules. PSCs (0.08 cm²) fabricated by the all-blading process reache an average efficiency of 22.4 ± 0.5% and a champion efficiency of 23.1% for perovskites with a bandgap of 1.51 eV, with much better stability compared to evaporated ETL PSCs. The all-bladed minimodule (25.03 cm²) shows an aperture efficiency of ≈19.3%, showing the good uniformity of the bladed ETLs.

A strain modulation strategy to constrain phase segregation in a wide-bandgap perovskite absorber by reinforcing the energy barrier for ion migration is reported. With compressive strain, the single-junction devices yield one of smallest voltage deficits of 440 mV. Moreover, the resulting perovskite/silicon tandem solar cells achieve a champion efficiency of 26.95% with improved light stability at open-circuit.

Abstract

Perovskite/silicon tandem solar cells are promising to penetrate photovoltaic market. However, the wide-bandgap perovskite absorbers used in top-cell often suffer severe phase segregation under illumination, which restricts the operation lifetime of tandem solar cells. Here, a strain modulation strategy to fabricate light-stable perovskite/silicon tandem solar cells is reported. By employing adenosine triphosphate, the residual tensile strain in the wide-bandgap perovskite absorber is successfully converted to compressive strain, which mitigates light-induced ion migration and phase segregation. Based on the wide-bandgap perovskite with compressive strain, single-junction solar cells with the n–i–p layout yield a power conversion efficiency (PCE) of 20.53% with the smallest voltage deficits of 440 mV. These cells also maintain 83.60% of initial PCE after 2500 h operation at the maximum power point. Finally, these top cells are integrated with silicon bottom cells in a monolithic tandem device, which achieves a PCE of 26.95% and improved light stability at open-circuit.

Nature, Published online: 13 April 2022; doi:10.1038/s41586-022-04455-0

Publication date: 1 July 2022

Source: Chemical Engineering Journal, Volume 439

Author(s): Xin Yin, Jifeng Zhai, Pingfan Du, Wei-Hsiang Chen, Lixin Song, Jie Xiong, Frank Ko

A new class of polymeric hole-transport materials (HTMs) was explored, featuring fluorine-substituted pyrene and specific Pb−Se secondary interactions. Perovskite solar cells (PSCs) using PE10 as dopant-free HTM, afforded an excellent PCE of 22.3 %, positioning it among the best PSCs based on dopant-free HTMs.

Abstract

A new class of polymeric hole-transport materials (HTMs) are explored by inserting a two-dimensionally conjugated fluoro-substituted pyrene into thiophene and selenophene polymeric chains. The broad conjugated plane of pyrene and “Lewis soft” selenium atoms not only enhance the π–π stacking of HTM molecules greatly but also render a strong interaction with the perovskite surface, leading to an efficient charge transport/transfer in both the HTM layer and the perovskite/HTM interface. Note that fluorine substitution adjacent to pyrene boosts the stacking of HTMs towards a more favorable face-on orientation, further facilitating the efficient charge transport. As a result, perovskite solar cells (PSCs) employing PE10 as dopant-free HTM afford an excellent efficiency of 22.3 % and the dramatically enhanced device longevity, qualifying it among the best PSCs based on dopant-free HTMs.

Publication date: 15 June 2022

Source: Nano Energy, Volume 97

Author(s): Yu-Jin Kang, Seok-In Na

A bottom-up infiltration method using HCOONH₄ as pre-buried additive in SnO₂ electron transport layer (ETL) enables a cross-layer defect manipulation throughout the SnO₂ ETL, perovskite layer, and their interface, along with a significantly reduced residual stress within perovskite film. As a result of the cross-layer treatment, a record power conversion efficiency of 22.37% (21.90% certified) is achieved on the optimized flexible perovskite solar cells.

Abstract

Halide perovskites have shown superior potentials in flexible photovoltaics due to their soft and high power-to-weight nature. However, interfacial residual stress and lattice mismatch due to the large deformation of flexible substrates have greatly limited the performance of flexible perovskite solar cells (F-PSCs). Here, ammonium formate (HCOONH₄) is used as a pre-buried additive in electron transport layer (ETL) to realize a bottom-up infiltration process for an in situ, integral modification of ETL, perovskite layer, and their interface. The HCOONH₄ treatment leads to an enhanced electron extraction in ETL, relaxed residual strain and micro-strain in perovskite film, along with reduced defect densities within these layers. As a result, a top power conversion efficiency of 22.37% and a certified 21.9% on F-PSCs are achieved, representing the highest performance reported so far. This work links the critical connection between multilayer mechanics/defect profiles of ETL-perovskite structure and device performance, thus providing meaningful scientific direction to further narrowing the efficiency gap between F-PSCs and rigid-substrate counterparts.

Publication date: 15 June 2022

Source: Nano Energy, Volume 97

Author(s): Yi-Ran Shi, Kai-Li Wang, Yan-Hui Lou, Ding-Bo Zhang, Chun-Hao Chen, Jing Chen, Yu-Xiang Ni, Senol Öz, Zhao-Kui Wang, Liang-Sheng Liao

Bulk and surface treatment of formamidium lead iodide perovskite with chlorine-based compounds promote an enhancement of the solar cell photovoltaic conversion efficiency (PCE), by simultaneously improving the active layer crystallinity and morphology, thus increasing the short-circuit current density, and suppressing nonradiative losses, boosting the device open-circuit voltage.

Defect-mediated recombination losses limit the open-circuit voltage (V _OC) of perovskite solar cells (PSCs), negatively affecting the device's performance. Bulk and dimensional engineering have both been reported as promising strategies to passivate shallow defects, thus improving the photovoltaic conversion efficiency (PCE). Here, a combined bulk and surface treatment employing chlorine-based compounds is employed. Methylammonium chloride (MACl) is used as a bulk additive, while 4-methylphenethylammonium chloride (MePEACl) is deposited onto the perovskite surface to produce a low-dimensional perovskite (LDP) and reduce nonradiative recombination. Through structural and morphological investigations, it can be confirmed that bulk and surface doping have a beneficial effect on the film morphology and its overall quality, while electroluminescence (EL) and photoluminescence (PL) analyses demonstrate an increased and more homogeneous emission. Applying this double passivation strategy in PSC fabrication, a boost is observed in both the short-circuit current density and the V _OC of the devices, achieving a champion 21.4% PCE while improving device stability.

An ionic liquid butylammonium acetate (BAAc) is introduced to PbI₂ to tune the crystallization of perovskites to improve device stability. The BAAc-treated devices show better thermal stability with maintaining 79.5% of initial efficiency after 700 h of aging at 85 °C in nitrogen environment, as compared to the pristine device that retained 47.2% of its initial efficiency after 312 h.

Long-term operational stability is a significant challenge for perovskite solar cells to become a commercial photovoltaic technology. Herein, a feasible approach is presented to improve both thermal and environmental stability of organic–inorganic hybrid perovskites by introducing ionic liquid butylammonium acetate (BAAc) to coordinate the PbI₂ precursor solution through strong bonding interactions to tune crystallization of perovskites. Inverted planar solar cells based on BAAc-containing tri-cation perovskites result in a high efficiency of over 20%. More importantly, after 700 h of aging at 85 °C in the nitrogen environment and 650 h storage in the ambient condition with a relative humidity of 35 ± 5%, the BAAc-treated devices are shown to be much more stable as maintained 79.5% and 76.3% of the initial power conversion efficiency, respectively. This work provides a promising strategy to tune crystallization of perovskites to improve long-term stability of perovskite solar cells.

Hydrophobic graphene quantum dots (HGQDs) containing amide linkages, which consist of carbonyl and dodecyl amine groups, are successfully applied as an efficient bifunctional interface modifier to simultaneously boost the power conversion efficiency and stability of perovskite solar cells.

Passivating the defects and grain boundaries (GBs) of perovskite films at the interface by interface engineering is a promising route to achieve efficient and stable perovskite solar cells (PSCs). Herein, a new type of graphene, that is, hydrophobic graphene quantum dots (HGQDs) containing amide linkages, which consist of carbonyl and dodecyl amine groups, is successfully used as a bifunctional interface modifier to engineer the interface of the perovskite/hole transport layer. A comprehensive characterization including X-ray photoelectron spectroscopy, Fourier-transform photocurrent spectroscopy, Raman spectroscopy, photoluminescence spectroscopy, and space-charge-limited current measurements is performed to identify the underlying passivation mechanisms. It can be demonstrated that the HGQDs, due to the bifunctional groups containing N and O atoms, effectively passivate the uncoordinated Pb²⁺ ions at the perovskite film surface and GBs and consequently induce a lower trap state density. Moreover, HGQDs enhance the quality of the perovskite film which reduces the charge recombination at the interface. Therefore, the power conversion efficiency of PSCs treated with HGQDs is significantly increased from 16.00% to 18.30%, mainly based on the improved open-circuit voltage and fill factor. Importantly, the HGQDs featuring hydrophobicity due to alkyl chains significantly enhance moisture stability.

An organic ferroelectric material poly(vinylidene fluoride):dabcoHReO₄ as a perovskite dopant can be partially polarized by the built-in electric field of perovskite solar cell (pero-SC) itself, which produces an additional electric field, thus promoting the charge-carrier transportation. A promising 24.23% power conversion efficiency (PCE) (certified PCE of 23.45%) and robust operational stability are obtained.

Abstract

The built-in electric field (BEF) intensity of silicon heterojunction solar cells can be easily enhanced by selective doping to obtain high power conversion efficiencies (PCEs), while it is challenging for perovskite solar cells (pero-SCs) because of the difficulty in doping perovskites in a controllable way. Herein, an effective method is reported to enhance the BEF of FA_0.92MA_0.08PbI₃ perovskite by doping an organic ferroelectric material, poly(vinylidene fluoride):dabcoHReO₄ (PVDF:DH) with high polarizability, that can be driven even by the BEF of the device itself. The polarization of PVDF:DH produces an additional electric field, which is maintained permanently, in a direction consistent with that of the BEF of the pero-SC. The BEF superposition can more sufficiently drive the charge-carrier transport and extraction, thus suppressing the nonradiative recombination occurring in the pero-SCs. Moreover, the PVDF:DH dopant benefits the formation of a mesoporous PbI₂ film, via a typical two-step processing method, thereby promoting perovskite growth with high crystallinity and a few defects. The resulting pero-SC shows a promising PCE of 24.23% for a 0.062 cm² device (certified PCE of 23.45%), and a remarkable PCE of 22.69% for a 1 cm² device, along with significantly improved moisture resistances and operational stabilities.

The potential leakage of lead from the degraded perovskite photovoltaic poses threats to the ecosystem. To trap the lead from degraded flexible perovskite solar modules (PVSMs), sulfonated graphene aerogels/polydimethylsiloxane is employed to serve as a lead-absorbing encapsulant. Over 99% of Pb²⁺ from the degraded PVSMs can be captured, which provides an effective strategy to realize safe-to-use perovskite-based flexible electronics.

Abstract

The potential leakage of lead from degraded perovskite photovoltaics poses a threat to the ecosystem and human health, which is a severe hurdle for their commercialization, especially for flexible modules that are often integrated in applications used in daily living. To trap the lead from degraded flexible perovskite solar modules (PVSMs), sulfonated graphene aerogels mixed with polydimethylsiloxane are employed to serve as lead-absorbing encapsulants on both sides of flexible PVSMs. The large specific area of sulfonated graphene aerogels and their high binding energy with Pb²⁺ give them superior lead adsorption capacity in aqueous solution. Over 99% of Pb²⁺ from the degraded flexible PVSMs can be captured by the encapsulant under different simulated conditions (scratching, bending, and thermal circling) to reduce the lead leakage to ≈10 ppb. Moreover, the lead from degraded flexible PVSMs can be minimized to far below the hazardous waste limit according to the resource conservation and recovery act regulation (RCRA). This work provides an effective strategy to realize safe-to-use perovskite-based flexible electronics to facilitate their commercialization.

Single-crystal solar cells with high efficiency and a superior weak light response are achieved by engineering the hole extraction interface. Remarkably enhanced efficiency of 22.1% under AM 1.5G irradiation and indoor efficiency of 39.2% under 1000 lux irradiation are obtained, which are both the highest values for MAPbI₃ single-crystal solar cells.

Abstract

Perovskite single crystals have recently been regarded as emerging candidates for photovoltaic application due to their improved optoelectronic properties and stability compared to their polycrystalline counterparts. However, high interface and bulk trap density in micrometer-thick thin single crystals strengthen unfavorable nonradiative recombination, leading to large open-circuit voltage (V _OC) and energy loss. Herein, hydrophobic poly(3-hexylthiophene) (P3HT) molecule is incorporated into a hole transport layer to interact with undercoordinated Pb²⁺ and promote ion diffusion in a confined space, resulting in higher-quality thin single crystals with reduced interface and bulk defect density, suppressed nonradiative recombination, accelerated charge transport, and extraction. As a result, a remarkably enhanced V _OC of up to 1.13 V and efficiency of 22.1% are achieved, which are both the highest values for MAPbI₃ single-crystal solar cells. Moreover, the reduced defect density and suppressed carrier recombination lead to superior weak light response of the single-crystal solar cells after incorporation of P3HT, and an indoor photovoltaic efficiency of 39.2% at 1000 lux irradiation is obtained.

The authors demonstrate that designing functional fullerenes with roles beyond defect passivation is essential for perovskite solar cells (PSCs). By taking the advantages of fullerene, porphyrin, and pentafluorophenyl, a novel fullerene-porphyrin dyad is intentionally synthesized to stitch grain boundaries and trap lead ions in the perovskite film by forming chemical interactions in-situ. This robust strategy yields high-performance and eco-friendly PSCs.

Abstract

Designing functional fullerenes with roles beyond defect passivation and electron-transporting for perovskite solar cells (PSCs) is essential to the development of fullerenes and PSCs. Here, the authors design and synthesize a functional fullerene, FPD, composed of a C₆₀ cage, a porphyrin ring, and three pentafluorophenyl groups. The structure features of FPD enable it can form chemical interactions with the perovskite lattices. These interactions enhance the defect passivation effect and prevent the decomposition of perovskite under irradiation. As a result, the FPD-based device yields an improved power conversion efficiency of 23% with substantially enhanced operational stability (T ₈₀ > 1500 h). Furthermore, once got damaged, the FPD can prevent lead leakage by forming a stable and water-insoluble complex (FPD-Pb). Their findings provide a novel strategy to achieve high-performance and eco-friendly PSCs with functional fullerene materials.