3D/2D multidimensional perovskites: Balance of high performance and stability for perovskite solar cells

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A non-wetting and conductive polyethylene dioxothiophene hole transport layer for scalable and flexible perovskite solar cells

The regulated crystallization of perovskite and highly repeatable preparation are decisive challenges for large-scale flexible perovskite solar cells(PSCs). Herein, we synthesize an oil-soluble poly(3,4-ethylenedioxythiophene)(Oil-PEDOT) as a hole transport layer(HTL). The non-wetting Oil-PEDOT HTL can promote the quality of large-area flexible perovskite films because of its optimized crystallinity and printability. The Oil-PEDOT layer also delivers desirable conductivity and charge transport without a complex doping. Consequently, the flexible PSCs with Oil-PEDOT HTL achieve an efficiency of 19.51% and 16.70%based on 1.05 and 22.50 cm~2, respectively. Moreover, these large-scale flexible PSCs demonstrate remarkable mechanical robustness, and the efficiency exhibits 93% retention after 7,000 bending cycles. These results show that the Oil-PEDOT is a potentially efficient HTL for fabricating efficient large-scale flexible PSCs.     

Improved interfacial property by small molecule ethanediamine for high performance inverted planar perovskite solar cells

We report a simple and effective method to realize desirable interfacial property for inverted planar perovskite solar cells(PSCs)by using small molecule ethanediamine for the construction of a novel polyelectrolyte hole transport material(P3CT-ED HTM).It is found that P3CT-ED can not only improve the hole transport property of P3CT-K but also improve the crystallinity of adjacent perovskite film.In addition,the introduction of ethanediamine into P3CT realigns the conduction and valence bands upwards,passivates surface defects and reduces nonradiative recombination.As a consequence,compared to P3CT-K hole transport layer(HTL)based devices,the average power conversion efficiency(PCE)is boosted from17.2% to 19.6% for the counterparts with P3CT-ED,with simultaneous enhancement in open circuit voltage and fill factor.The resultant device displays a champion PCE of 20.5% with negligible hysteresis.     

Defect mitigation using d-penicillamine for efficient methylammonium-free perovskite solar cells with high operational stability

Trap-dominated non-radiative charge recombination is one of the key factors that limit the performance of perovskite solar cells (PSCs), which was widely studied in methylammonium (MA) containing PSCs. However, there is a need to elucidate the defect chemistry of thermally stable, MA-free, cesium/formamidinium (Cs/FA)-based perovskites. Herein, we show that d-penicillamine (PA), an edible antidote for treating heavy metal ions, not only effectively passivates the iodine vacancies (Pb²⁺ defects) through coordination with the –SH and –COOH groups in PA, but also finely tunes the crystallinity of Cs/FA-based perovskite film. Benefiting from these merits, a reduction of non-radiative recombination and an increase in photoluminescence lifetime have been achieved. As a result, the champion MA-free device exhibits an impressive power conversion efficiency (PCE) of 22.4%, an open-circuit voltage of 1.163 V, a notable fill factor of 82%, and excellent long-term operational stability. Moreover, the defect passivation strategy can be further extended to a mini module (substrate: 4 × 4 cm², active area: 7.2 cm²) as well as a wide-bandgap (∼1.73 eV) Cs/FA perovskite system by delivering PCEs of 16.3% and 20.2%, respectively, demonstrating its universality in defect passivation for efficient PSCs.

Iodine vacancy defects in MA-free perovskite are effectively passivated through the interaction between Pb²⁺ and the functional groups in d-penicillamine, resulting in an impressive efficiency of 22.4% along with excellent operational stability.     

Cross-linked polyelectrolyte reinforced SnO2 electron transport layer for robust flexible perovskite solar cells

SnO₂ electron transport layer(ETL) is a vital component in perovskite solar cells(PSCs), due to its excellent photoelectric properties and facile fabrication process. In this study, we synthesized a water-soluble and adhesive polyelectrolyte with ethanolamine(EA) and poly-acrylic acid(PAA). The linear PAA was crosslinked by EA, forming a 3D network that stabilized the SnO₂ nanoparticle dispersion. An organic–inorganic hybrid ETL is developed by introducing the cross-linked ...     

Application of phenonaphthazine derivatives as hole-transporting materials for perovskite solar cells

Two electron-rich,solution-processable phenonaphthazine derivatives,5,12-bis{N-[4,4’-bis-（phenyl）-aminophen-4’’-yl]}-phenonaphthazine（BPZTPA） and 5,12-bis{N-[4,4’-bis（methoxy-phenyl）aminophen-4’’-yl]}-phenonaphthazine（Me O-BPZTPA） have been designed and employed in the fabrication of perovskite solar cells.BPZTPA and Me O-BPZTPA exhibit excellent thermal stabilities,hole mobilities（～10-4cm²/（V.s）） and suitable HOMO levels（-5.34 and-5.29 e V,respectively） relative to the valence band of the CH₃NH₃ Pb I₃ and Au work function,showing their potential as alternative hole-transporting materials（HTMs）.Meanwhile,the corresponding mesoporous Ti O₂/CH₃NH₃ Pb I₃/HTM/Au devices are investigated,and the best power conversion efficiency of 10.36% has been achieved for Me O-BPZTPA without using p-type dopant.     

A reaction-and-assembly approach using monoamine zinc porphyrin for highly stable large-area perovskite solar cells

Inhibiting the irreversible escape of organic cations and iodide species in perovskite films is crucial for the fabrication of efficient and stable perovskite solar cells(PSCs). Here, we develop a reaction-and-assembly approach using monoamine zinc porphyrin(ZnP) to modify methylammonium(MA~+) lead iodide perovskite film. The amine group in ZnP reacts with MA~+ and I~- ions to yield monoammonium zinc porphyrin(ZnP-H+I-). The resultant films show no escape of iodide when immersed in ether solutions. Measurements from space-charge limited currents and transient photoluminescence indicate the modified films have reduced density of defects. These results suggest the formed ZnP-H~+I~- is bound on the surface and grain boundary of perovskite film to retard migrations of ions. DFT calculations also show that the energy alignment between ZnP-H~+ and perovskite facilitates the electron transfer and reduces charge recombination at the perovskite grains. Furthermore, post-treating the Zn Pdoped film with ZnP again results in the formation of a one dimension zig-zag coordination polymer on the surface of the perovskite film. The single crystal structure of ZnP shows the polymer layer is formed through the coordination interaction between the Zn(II) metal center and a neighboring monoamine. The polymer facilitates the interfacial charge transfer, and reduces the escape of organic cations and iodide species in perovskite films, thereby keeping the excellent cell performance(20.0%) and further realizing the ion encapsulation. Finally, the modified PSCs retain over 90% of its original efficiency over2,000 h at 85 °C or AM 1.5 G continuous illumination, or over 6,000 h in 45% humidity without encapsulation. This work affords a new strategy to achieve the efficient ions immobilization and encapsulation by in situ reaction and coordination assembly of mono-amine zinc porphyrin.     

Reductive ionic liquid-mediated crystallization for enhanced photovoltaic performance of Sn-based perovskite solar cells

Tin (Sn)-based perovskite solar cells (PSCs) have recently made inspiring progress,and certified power conversion efficiency(PCE) has reached impressive value of 14.8%.However,it is still challenging to realize efficient and stable 3D Sn-based PSCs due to the fast crystallization and easy Sn²⁺oxidation of Sn-based perovskite.Herein,we reported the utilization of a reductive ionic liquid,methylamine formate (MAFa),to drive the controlled crystallization process and suppress Sn²⁺     

A crosslinked polymer as dopant-free hole-transport material for efficient n-i-p type perovskite solar cells

A new crosslinked polymer,called P65,with appropriate photo-electrochemical,opto-electronic,and thermal properties,has been designed and synthesized as an efficient,dopant-free,hole-transport material(HTM)for n-i-p type planar perovskite solar cells(PSCs).P65 is obtained from a low-cost and easily synthesized spiro[fluorene-9,90-xanthene]-30,60-diol(SFX-OH)-based monomer X65 through a freeradical polymerization reaction.The combination of a three-dimensional(3 D)SFX core unit,holetransport methoxydiphenylamine group,and crosslinked polyvinyl network provides P65 with good solubility and excellent film-forming properties.By employing P65 as a dopant-free hole-transport layer in conventional n-i-p type PSCs,a power conversion efficiency(PCE)of up to 17.7%is achieved.To the best of our knowledge,this is the first time a 3 D,crosslinked,polymeric dopant-free HTM has been reported for use in conventional n-i-p type PSCs.This study provides a new strategy for the future development of a 3 D crosslinked polymeric dopant-free HTM with a simple synthetic route and low-cost for commercial,large-scale applications in future PSCs.     

Supersaturation controlled growth of MAFAPbI_3 perovskite film for high efficiency solar cells

Controlling the nucleation and growth of organic-inorganic hybrids perovskite is of key importance to improve the morphology and crystallinity of perovskite films. However, the growth mechanism of perovskite films based on classical crystallization theory is not fully understood. Here, we develop a supersaturation controlled strategy(SCS) to balance the nucleation and crystal growth speeds. By this strategy, we are able to find an ideal supersaturation region to realize a balance of nucleation and crystal growth, which yields highly crystallized perovskite films with micrometer-scale grains. Besides, we provide a thoughtful analysis of nucleation and growth based on the fabrication of the perovskite films. As a result, the highest photovoltaic power conversion efficiencies(PCE) of 19.70% and 20.31% are obtained for the planar and the meso-superstructured devices, respectively. This strategy sheds some light for understanding the film growth mechanism of high quality perovskite film, and it provides a facile strategy to fabricate high efficiency perovskite solar cells.     

Effect of additives on the photovoltaic performance of coumarin-dye-sensitized nanocrystalline TiO2 solar cells

The effects of deoxycholic acid (DCA) and 4-tert-butylpyridine (TBP) as additives on the photovoltaic performance of coumarin-dye-sensitized nanocrystalline TiO2 solar cells were investigated. DCA coadsorption improved both the photocurrent and photovoltage of the solar cells, even though it decreased the amount of dye adsorbed on the TiO2 electrode. The improved photocurrent may arise from suppression of the deactivation of the excited state via quenching processes between dye molecules or a more negative LUMO level of the dye in the presence of DCA, resulting in a high electron-injection yield from the dye into TiO2. The increased photovoltage is probably due to suppression of recombination between the injected electrons and I3- ions on the TiO2 surface (dark current). The addition of TBP to the electrolyte also markedly improved the photovoltage and fill factor of the solar cell, and consequently, the total conversion efficiency increased from 3.6% to 7.5%. FT-IR spectroscopy indicated that a large amount of TBP was adsorbed on the dye-coated TiO2 films in the presence of Li cations. This result suggests that TBP, like DCA, suppressed the dark current on the TiO2 surface, which resulted in the improved photovoltage.     

Scalable spray coated high performance sulfurized electron transporter for efficient and stable perovskite solar modules

The stability issue has been acknowledged as the bottleneck in the practical application of perovskite photovoltaics, while the stabilized interface between the perovskites and charge transport layers dominates their stability performance under different stresses. Here, we developed a high-performance sulfurized zinc-titanium mixed oxide(ZTO-S) electron transport layer(ETL) to fabricate large-area efficient and long-term 85 °C/85% RH stable perovskite solar modules. The scalably prepared ZTO-S u...     

Electrodeposition of porous CuSCN layers as hole-conducting material for perovskite solar cells

One of the most promising among hole-conducting materials, CuSCN, was prepared for the first time in a form of porous layers for potential applications in inverted perovskite solar cells.     

钙钛矿太阳能电池的商业化进展与挑战

钙钛矿太阳电池是一项颠覆性的光伏技术,具有能量转化效率高、生产成本低、制备工艺简单等优势。当前,钙钛矿太阳能电池的认证效率已达25.7%,但其面临着严重的商业化瓶颈,如稳定性差、模组效率相对低、铅毒性等,且这些问题相互关联。本文简述了钙钛矿太阳能电池的工作原理和器件结构,并归纳总结了在解决钙钛矿太阳能电池稳定性、封装和模组化等商业化瓶颈问题方面的主要研究进展。最后,本文提出了钙钛矿光伏商业化进程中值得关注的解决措施。     

Benzimidazolyl functionalized ionic liquids as an additive for high performance dye-sensitized solar cells

Benzimidazolyl functionalized ionic liquids were synthesized and applied as additives for dye-sensitized solar cells. The fabricated devices show an overall power conversion efficiency of ~7.79% under AM 1.5 radiation (50 mW cm(-2)), and an excellent long-term stability.     

Two-dimensional perovskite capping layer for stable and efficient tin-lead perovskite solar cells

Mixed tin-lead iodide perovskites exhibit the characteristics of low toxicity and improved light harvesting ability up to nearinfrared(NIR) spectral region, making them as an attractive alternative for traditional lead based perovskites. However, the performance of lead-based perovskites solar cells is still far inferior to their lead analogues owing to the unavoidable oxidation of Sn~(2+)to Sn~(4+). Here we introduced two-dimensional(2D) perovskite on the top of three dimensional(3D) perovskite film as a capping layer to reduce the self-oxidation, and thus improved the device stability. 2D capping layer was then confirmed by X-ray diffraction(XRD) and X-ray photoelectron spectroscopy(XPS) analysis. The existence of the 2D protecting thin layer significantly reduce the spontaneous Sn~(2+)oxidation, thus improve the device performance and reduce the hysteresis. The phenomena could be ascribed to the improved charge extraction efficiency causing by prohibited nonradiative recombination. On top of this, the photovoltaic devices based on conventional-structure configuration were fabricated. Taking advantage of the 2D capping layer, 2D/3D hybrid perovskite photovoltaic devices achieve a open-circuit voltage(Voc) of 0.77 V with short circuit current density(Jsc) of 26.60 mA cm~(-2), delivering the best-performing power conversion efficiency of 15.5%. Moreover, the 2D/3D perovskite devices maintained 60% its initial efficiency after 40 h exposed in air(humidity around 30%, temperature 22 °C),while 3D perovskite-based devices completely failed.     

Surface-functionalized hole-selective monolayer for high efficiency single-junction wide-bandgap and monolithic tandem perovskite solar cells

Carbazole moiety-based 2PACz([2-(9H-carbazol-9-yl)ethyl]phosphonic acid) self-assembled monolayers(SAMs) are excellent hole-selective contact(HSC) materials with abilities to excel the charge-transferdynamics of perovskite solar cells(PSCs). Herein, we report a facile but powerful method to functionalize the surface of 2PACz-SAM, by which reproducible, highly stable, high-efficiency wide-bandgap PSCs can be obtained. The 2PACz surface treatment with various donor number solvents improves assembl...     

Synergistic effect of TiO_2 hierarchical submicrospheres for high performance dye-sensitized solar cells

The performance of dye-sensitized solar cells(DSCs) could be improved by using rationally designed mesoporous film structure for electron collection, dye adsorption and light scattering. The development of a novel double layer film prepared by TiO_2 hierarchical submicrospheres and nanoparticles was reported in this article. The submicrospheres were composed of rutile nanorods of 10 nm diameter and the length of 150–250 nm, which facilitated fast electron transport, charge collection and light scattering. Using a double layer structure consisting of the 10 wt% film as a dye loading layer and the 50 wt% film as the light scattering layer, C101 sensitizer and liquid electrolyte, DSC yielded power conversion efficiency of 9.68% under 1 sun illumination.     

Fullerene derivative acceptors for high performance polymer solar cells

Polymer solar cells (PSCs) are composed of a blend film of a conjugated polymer donor and a soluble fullerene derivative acceptor sandwiched between a PEDOT?:?PSS coated ITO positive electrode and a low workfunction metal negative electrode. The conjugated polymer donor and the fullerene derivative acceptor are the key photovoltaic materials for high performance PSCs. For the acceptors, although [6,6]-phenyl-C(61)-butyric acid methyl ester (PC(60)BM) and its corresponding C(70) derivative PC(70)BM are dominantly used as the acceptors in PSC at present, several series of new fullerene derivatives with higher-lying LUMO energy level and better solubility were reported in recent years for further improving the power conversion efficiency of the PSCs. In this perspective paper, we reviewed the recent research progress on the new fullerene derivative acceptors, including various PC(60)BM-like C(60) derivatives, PC(60)BM bisadduct, PC(70)BM bisadduct, indene-C(60) bisadduct and indene-C(70) bisadduct, trimetallic nitride endohedral fullerenes and other C(60) derivatives with multi side chains. The synthesis and physicochemical properties of PC(60)BM and PC(70)BM were also introduced considering the importance of the two fullerene acceptors.     

Enhanced efficiency and stability of perovskite solar cells by 2D perovskite vapor-assisted interface optimization

Organic–inorganic perovskites solar cells(PSCs)have attracted great attention due to their rapid progress in power conversion efficiency(PCE).However,there is still an enormous challenge to achieve both high efficiency and stability devices as the decomposition of perovskite materials under humid and light conditions.Herein,we demonstrate that high efficiency and stability of PSCs can be obtained by the reaction of three-dimensional(3D)perovskite with 1,4-butanediamine iodide(BEAI2)vapor.The incorporation of BEAI2 intensively promotes the crystallization of perovskite film with large grain size(~500 nm).Further characterization reveals that the post-treatment perovskite film delivered low interface trap density with long carrier lifetime(>200 ns),long carrier diffusion length(>600 nm)and large carrier mobility(>1.5 cm^2 V-1S-1).Solar cells employing such post-treatment films demonstrated 19.58%PCE without hysteresis.Moreover,the post-treatment devices can retain over 90%original efficiencies stored under ambient atmospheric conditions and exhibit better stability under 85℃and continuous illumination as a two-dimensional(2D)perovskite thin layer is formed on the surface/or at the grain boundaries of 3D perovskite.This study offers an effective way to obtain PSCs with high efficiency and stability.