Chen Weijie

Publication date: July 2024

Source: Journal of Energy Chemistry, Volume 94

Author(s): Guohui Luo, Linfeng Zhang, Liyun Guo, Xiuhong Geng, Penghui Ren, Yi Zhang, Haihua Hu, Xiaoping Wu, Lingbo Xu, Ping Lin, Haiyan He, Xuegong Yu, Peng Wang, Can Cui

A series of halogenated solid additives are designed, whose benzene unit interacting sites with PM6 are found to vary with the electrostatic potential, to tune the structural order and molecular orientation of PM6, leading to a maximum power conversion efficiency of 19.4%.

Abstract

Polymeric semiconducting materials struggle to achieve fast charge mobility due to low structural order. In this work, five 1H-indene-1,3(2H)dione-benzene structured halogenated solid additives namely INB-5F, INB-3F, INB-1F, INB-1Cl, and INB-1Br with gradually varied electrostatic potential are designed and utilized to regulate the structural order of polymer donor PM6. Molecular dynamics simulations demonstrate that although the dione unit of these additives tends to adsorb on the backbone of PM6, the reduced electrostatic potential of the halogen-substituted benzene can shift the benzene interacting site from alkyl side chains to the conjugated backbone of PM6, not only leading to enhanced π–π stacking in out-of-plane but also arising new π–π stacking in in-plane together with the appearance of multiple backbone stacking in out-of-plane, consequent to the co-existence of face-on and edge-on molecular orientations. This molecular packing transformation further translates to enhanced charge transport and suppressed carrier recombination in their photovoltaics, with a maximum power conversion efficiency of 19.4% received in PM6/L8-BO layer-by-layer deposited organic solar cells.

It is reported on a facile strategy to modify the ZnO electron transport layer (ETL) with formamidine disulfide dihydrochloride (FADD). It is found that the FADD modification leads to efficient defects passivation and stress dissipation at the CsPbI₂Br/ZnO interface. As a result, the inverted devices exhibit good photovoltaic performance and high thermal/mechanical stability on both rigid and flexible substrates.

Abstract

All inorganic CsPbI₂Br perovskite (AIP) has attracted great attention due to its excellent resistance against thermal stress as well as the remarkable capability to deliver high-voltage output. However, CsPbI₂Br perovskite solar cells (PeSCs) still encounter critical challenges in attaining both high efficiency and mechanical stability for commercial applications. In this work, formamidine disulfide dihydrochloride (FADD) modified ZnO electron transport layer (ETL) has been developed for fabricating inverted devices on either rigid or flexible substrate. It is found that the FADD modification leads to efficient defects passivation, thereby significantly reducing charge recombination at the AIP/ETL interface. As a result, rigid PeSCs (r-PeSCs) deliver an enhanced efficiency of 16.05% and improved long-term thermal stability. Moreover, the introduced FADD can regulate the Young's modulus (or Derjaguin-Muller-Toporov (DMT) modilus) of ZnO ETL and dissipate stress concentration at the AIP/ETL interface, effectively restraining the crack generation and improving the mechanical stability of PeSCs. The flexible PeSCs (f-PeSCs) exhibit one of the best performances so far reported with excellent stability against 6000 bending cycles at a curvature radius of 5 mm. This work thus provides an effective strategy to simultaneously improve the photovoltaic performance and mechanical stability.

An innovative ultrahigh humidity treatment strategy aimed at controlling the distribution of FAI in the sequentially vapor-deposited precursor perovskite thin film is developed. By implementing this ultrahigh humidity treatment strategy, stable perovskite solar cells through sequential vapor deposition, achieving an exceptional champion PCE of 22% even under high deposition rates, are successfully developed.

Abstract

The quality of two-step processed perovskites is significantly influenced by the distribution of organic amine salts. Especially, modulating the distribution of organic amine salts remains a grand challenge for sequential vapor-deposited perovskites due to the blocking effect of bottom compact PbI₂. Herein, an ultrahigh humidity treatment strategy is developed to facilitate the diffusion of formamidinium iodide (FAI) from the top surface to the buried bottom interface on the sequential vapor-deposited bilayer structure. Both experimental and theoretical investigations elucidate the mechanism that moisture helps to i) create FAI diffusion channels by inducing a phase transition from α- to δ-phase in the perovskite, and ii) enhance the diffusivity of FAI by forming hydrogen bonds. This ultrahigh humidity treatment strategy enables the formation of a desired homogeneous and high-quality α-phase after annealing. As a result, a champion efficiency of 22.0% is achieved and 97.5% of its initial performance is maintained after aging for 1050 h under ambient air with a relative humidity of up to 80%. This FAI diffusion strategy provides new insights into the reproducible, scalable, and high-performance sequential vapor-deposited perovskite solar cells.

In this work, a high-molecular-weight polyvinyl pyrrolidone (PVP) is introduced into inverted perovskite solar cells as a robust multi-functional interlayer to engineer the buried interface. The interaction energies derived from theory calculations imply PVP predominately interacts with ammonium cations to form the hydrogen-bond polymer-ammonium intermediates, thus largely retarding the perovskite crystallization, consequently affording higher open-circuit voltage and superior power conversion efficiency.

Abstract

Perovskite interfaces where defects enrich are pivotal for both device efficiency and stability. Herein, a high-molecular-weight polyvinyl pyrrolidone (PVP) is proposed as a robust multi-functional interlayer to engineer the buried interface. Besides the well-known defect passivation, perovskite crystallization is intriguingly modulated via the formation of hydrogen-bond-based polymer-ammonium intermediates (e.g., PVP-FA+ or PVP-MA+, where MA and FA are methylamine and formamidine, respectively). The interaction energies derived from density functional theory calculations (−34.5, −26.8, and −9.9 kcal mol⁻¹ for PVP-FA⁺, PVP-MA⁺, and PVP-Pb²⁺) suggest that PVP predominately interacts with ammonium cations to form the intermediates, thus largely excluding other chemical interactions and retarding the perovskite crystallization. As such, the hydrophilic PVP interlayer leads to spontaneous perovskite spreading yet a counterintuitively similar nucleation density with respect to the hydrophobic poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), a change of preferred crystal orientation, improved crystallinity, and remarkably suppressed non-radiative recombination. These conducive effects jointly minimize the open-circuit voltage loss and give rise to superior power conversion efficiency for small-area and large-area devices.

A high-hole mobility pyrene-based organic semiconductor as an effective and universal hole transport layer additive is developed to achieve both high efficiency and stability in perovskite solar cells.

Abstract

Organic small molecules have been proven to be the most efficient and predominantly employed hole transport layers (HTLs) in perovskite solar cells (PSCs), the reliance of HTLs on additives like Li-TFSI has been unavoidable, particularly in terms of the well-known Spiro-OMeTAD. However, Li-TFSI aggregation in HTL results in the decreased performance and stability of PSCs with serious hysteresis. It is an urgent need to explore a universal strategy to solve Li-TFSI-induced issues. Herein, a pyrene-based organic semiconductor (PC) as an effective and universal additive for HTL application is developed. It is found that the introduction of PC can efficiently improve the hot carriers extraction/transfer and reduce the charge recombination in the device. Consequently, PSCs based on Spiro-OMeTAD+PC as a HTL exhibit an excellent PCE of 24.80% with a negligible hysteresis, much higher than the control device (22.14%). Additionally, the efficiency of the PC incorporated into another well-known X60 HTL-treated device is enhanced to 24.12% from the control device (22.04%), confirming its universal application in PSCs. Moreover, PC can effectively suppress the Li⁺ aggregation in HTL, and the unencapsulated PSCs exhibit high stability. The findings in this work provide an effective and universal avenue to construct highly efficient and stable PSCs.

In this study, two A-π-A'DA’-π-A-type NFAs are synthesized, namely T6 and T9, for the first time. Both T6- and T9-based cells exhibit efficiencies exceeding 10%. These initial findings underscore the significant potential of the DBTPT unit in the development of novel NFAs, aimed at enhancing the performance of OPV cells.

Abstract

The central core in non-fullerene acceptors (NFAs) plays a crucial role in determining the efficiency of organic photovoltaic (OPV) cells. To further advance the development of OPV cells, it is crucial to synthesize novel central cores for constructing high-performance NFAs. Here, dibenzothiadiazolopyrrolothiophene (DBTPT) is introduced, a ladder-type [1,2,5]thiadiazolo[3,4-e]indole-fused pentacyclic thiophene unit, into photovoltaic materials. By employing the DBTPT unit as the rigid molecular backbone and modifying the side chain of the thiophene π-bridge, two new acceptor-π-acceptor’-donor-acceptor’-π-acceptor (A-π-A'DA’-π-A)-type acceptors (T6 and T9) are synthesized. The effects of lateral alkyl and alkoxy side chains on the optoelectronic properties, charge transport, and molecular packing order are systematically investigated. When blended with polymer donor Poly[(2,6-(4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)-benzo[1,2-b:4,5-b']dithiophene))-alt-(5,5-(1',3'-di-2-thienyl-5'7'-bis(2-ethylhexyl)benzo[1',2'-c:4',5'-c']dithiophene-4,8-dione))] (PBDB-T), the blend film based on T9 with alkoxy side chains shows favorable molecular stacking and phase separation, resulting in excellent charge transfer performance. Benefiting low energetic disorder, PBDB-T:T9-based cell achieves an efficiency of 12.6% with a markedly low energy loss of 0.568 eV. The preliminary results demonstrate that the DBTPT unit has great potential for the construction of novel NFAs for high-performance OPV cells.

The PM6: BTP-eC9-based large-area (28.82 cm²) modules yield an impressive power conversion efficiency of 16.04% with a small cell-to-module loss. The result suggests the effectiveness of the volatile solid additive methyl nicotinate in regulating the active layer morphology and paves a new path for the fabrication of highly efficient and scalable large-area organic solar cell modules with non-halogenated solvent.

Abstract

The critical step in commercializing organic solar cells (OSCs) involves achieving high-performance modules through environmentally friendly solvents. The incorporation of solid additives, recognized as an effective method for modulating the morphology of active layers through layer-by-layer (LBL) deposition, plays a significant role. Here, a novel volatile solid additive is introduced individually into the non-halogenated solution of donor PM6 as a morphology-modulating agent. The additive induces conformational and crystalline orientation change of PM6, resulting in enhanced and balanced charge transport in the active layer. With a focus on exciton dynamics, the optimized active layer inhibits the formation of low-energy triplet states. It facilitates strong reverse hole transfer processes, leading to more efficient exciton dissociation. The final small-area LBL blade-coated OSCs fabricated under ambient conditions achieve a power conversion efficiency (PCE) of 18.42%. Furthermore, a large-area module with an area of 28.82 cm² is manufactured, achieving a PCE of 16.04% with a high geometric fill factor of 93.8%. This highlights the effective modulation of the active layer through the use of solid additives and provides a successful strategy for fabricating high-performance OSC modules with non-halogenated solvents.

A molecular bridge is introduced at the flexible SnO₂/perovskite interface to simultaneously achieve in situ bottom-up crystallization modulation and interfacial passivation utilizing organic bifunctional passivator sodium 2-cyanoacetate (SZC). The flexible indoor perovskite solar cells deliver an exceptional 41.33% at 1000 lux with a high fill factor of 84.32%.

Abstract

A robust perovskite-buried interface is pivotal for achieving high-performance flexible indoor photovoltaics as it significantly influences charge transport and extraction efficiency. Herein, a molecular bridge strategy is introduced utilizing sodium 2-cyanoacetate (SZC) additive at the perovskite-buried interface to simultaneously achieve in situ passivation of interfacial defects and bottom-up crystallization modulation, resulting in high-performance flexible indoor photovoltaic applications. Supported by both theoretical calculations and experimental evidences, it illustrates how SZCs serve as molecular bridges, establishing robust bonds between SnO₂ transport layer and perovskite, mitigating oxygen vacancy defects and under-coordinated Pb defects at interface during flexible fabrication. This, in turn, enhances interfacial energy level alignment and facilitates efficient carrier transport. Moreover, this in situ investigation of perovskite crystallization dynamics reveals bottom-up crystallization modulation, extending perovskite growth at the buried interface and influencing subsequent surface recrystallization. This results in larger crystalline grains and improved lattice strain of the perovskite during flexible fabrication. Finally, the optimized flexible solar cells achieve an impressive efficiency exceeding 41% at 1000 lux, with a fill factor as high as 84.32%. The concept of the molecular bridge represents a significant advancement in enhancing the performance of perovskite-based flexible indoor photovoltaics for the upcoming era of Internet of Things (IoT).

High-performance organic photovoltaic (OVP) with efficiency exceeding 20% is achieved via the self-assembled interlayer (SAI) strategy. The use of 2PACz-SAI advances the surface/interface optoelectronic properties, including mitigated parasitic absorption, improved optical field distribution and the carrier dynamics. Moreover, the efficacy of SAI strategy is widely proved. Additionally, the 2PACz-SAI based ST-OPV exhibits a record light utilization efficiency of 5.34%.

Abstract

Interfacial layers (ILs) are prerequisites to form the selective charge transport for high-performance organic photovoltaics (OPVs) but mostly result in considerable parasitic absorption loss. Trimming the ILs down to a mono-molecular level via the self-assembled monolayer is an effective strategy to mitigate parasitic absorption loss. However, such a strategy suffers from inferior electrical contact with low surface coverage on rough surfaces and poor producibility. To address these issues, here, the self-assembled interlayer (SAI) strategy is developed, which involves a thin layer of 2–6 nm to form a full coverage on the substrate via both covalent and van der Waals bonds by using a self-assembled molecule of 2-(9H-carbazol-9-yl) (2PACz). Via the facile spin coating without further rinsing and annealing process, it not only optimizes the electrical and optical properties of OPVs, which enables a world-record efficiency of 20.17% (19.79% certified) but also simplifies the tedious processing procedure. Moreover, the SAI strategy is especially useful in improving the absorbing selectivity for semi-transparent OPVs, which enables a record light utilization efficiency of 5.34%. This work provides an effective strategy of SAI to optimize the optical and electrical properties of OPVs for high-performance and solar window applications.

A macromer PIBA is carefully designed as a UV-curable adhesive for blanket encapsulating perovskite solar cells (pero-SC) without sacrificing the device efficiency. More importantly, the resultant CPIBA-BE pero-SCs retain >95% of their initial efficiencies after the damp test (85% relative humidity) for 2000 h.

Abstract

Perovskite solar cells (pero-SCs) are highly unstable even under trace water. Although the blanket encapsulation (BE) strategy applied in the industry can effectively block moisture invasion, the commercial UV-curable adhesives (UVCAs) for BE still trigger power conversion efficiency deterioration, and the degradation mechanism remains unknown. For the first time, the functions of commercial UVCAs are revealed in BE-processed pero-SCs, where the small-sized monomer easily permeates to the perovskite surface, forming an insulating barrier to block charge extraction, while the high-polarity moiety can destroy perovskite lattice. To solve these problems, a macromer, named PIBA is carefully designed, by grafting two acrylate terminal groups on the highly gastight polyisobutylene and realizes an increased molecular diameter as well as avoided high-polarity groups. The PIBA macromer can stabilize on pero-SCs and then sufficiently crosslink, forming a compact and stable network under UV light without sacrificing device performance during the BE process. The resultant BE devices show negligible efficiency loss after storage at 85% relative humidity for 2000 h. More importantly, these devices can even reach ISO 20653:2013 Degrees of protection IPX7 standard when immersed in one-meter-deep water. This BE strategy shows good universality in enhancing the moisture stability of pero-SCs, irrespective of the perovskite composition or device structure.

This work proposed a new doping strategy by constructing a cascade reaction in organic hole transport layer (HTL) to achieve high-efficiency perovskite solar cells (PSCs). Owing to the dual functions of cascade reaction that is rapid and efficient oxidation and inhibition of sustained erosion from 4-tert-butylpyridine to perovskite, the PSCs with Spiro-OMeTAD exhibit a champion power conversion efficiency of 25.76 % (certificated of 25.38 %) with good reproducibility and stability.

Abstract

The doped organic hole transport layer (HTL) is crucial for achieving high-efficiency perovskite solar cells (PSCs). However, the traditional doping strategy undergoes a time-consuming and environment-dependent oxidation process, which hinders the technology upgrades and commercialization of PSCs. Here, we reported a new strategy by introducing a cascade reaction in traditional doped Spiro-OMeTAD, which can simultaneously achieve rapid oxidation and overcome the erosion of perovskite by 4-tert-butylpyridine (tBP) in organic HTL. The ideal dopant iodobenzene diacetate was utilized as the initiator that can react with Spiro to generate Spiro⋅⁺ radicals quickly and efficiently without the participation of ambient air, with the byproduct of iodobenzene (DB). Then, the DB can coordinate with tBP through a halogen bond to form a tBP-DB complex, minimizing the sustained erosion from tBP to perovskite. Based on the above cascade reaction, the resulting Spiro-based PSCs have a champion PCE of 25.76 % (certificated of 25.38 %). This new oxidation process of HTL is less environment-dependent and produces PSCs with higher reproducibility. Moreover, the PTAA-based PSCs obtain a PCE of 23.76 %, demonstrating the excellent applicability of this doping strategy on organic HTL.

Two low-cost electron acceptors of DTB2 and DTB3 are reported. After moving the branching position, both acceptors show distinct aggregation behavior. The DTB3-based device exhibits an outstanding power conversion efficiency (PCE) of up to 15.3%.

The state-of-the-art bulk-heterojunction (BHJ) organic solar cells (OSCs) typically include expensive fused-ring electron acceptors, hindering industrialization. Designing low-cost and highly efficient electron acceptors remains challenging. Herein, two low-cost electron acceptors (DTB2 and DTB3) based on a conjugated 1,4-di(thiophen-2-yl)benzene (DTB) core and two fluorinated 2-(3-oxo-2,3-dihydroinden-1-ylidene)malononitrile end-groups are reported. Their only difference is the alkyl chain branching position on the benzene ring. Both acceptors exhibit similar low optical gaps of ≈1.35 eV but different molecular orientations. DTB2 shows an edge-on arrangement, while DTB3, with a shift in branching positions toward the conjugated backbone, produces a face-on arrangement. Such molecular orientations are maintained in their BHJ layers after blending with a polymer donor PBQx-TF. The PBQx-TF:DTB3 film demonstrates superior BHJ phase-separation and faster charge carrier generation (0.44 ps) than those of the PBQx-TF:DTB2 film (50 ps). As a result, the DTB2-based OSC achieves a modest power conversion efficiency (PCE) of 8.5%. While the DTB3-based OSC produces an outstanding PCE of 15.3%, which is much higher than those of the reported DTB-based OSCs. Besides, DTB3 has a figure of merit up to 0.46, higher than the state-of-the-art fused-ring electron acceptors. This work provides new insights into designing low-cost and highly efficient electron acceptors.

The new composite transparent electrode system has excellent applicability for semitransparent perovskite solar cells (ST-PSCs), effectively addressing the challenges of low fill factors and power conversion efficiency, and presents a general and viable approach for fabricating efficient ST-PSCs.

In the quest to develop efficient semitransparent perovskite solar cells (ST-PSCs), the primary challenge lies in transparent electrode fabrication. n–i–p-type ST-PSCs often suffer from low fill factors (FF) and power conversion efficiency (PCE), attributed to the undesirable buffer layer/transparent conductive oxide combination of the transparent electrode. In this context, this study proposes an efficient composite transparent electrode (CTE) system comprising an ultrathin MoO₃ buffer layer (5 nm) and low-power sputtered indium zinc oxide (45 W–220 nm). The electrode demonstrates excellent compatibility with Spiro-OMeTAD-based devices, effectively addressing the low FF and PCE challenges of ST-PSCs. Employing the new CTE, the best-performing ST-PSCs with the absorption edge at 1.57 eV achieve a remarkable PCE of 21.96% with an FF of up to 83.80%. More transparent ST-PSCs with thickness-modulated absorbers and average transmittance of 50.77% at 600–1200 nm wavelength result in a PCE of up to 20.91% with the highest known FF of 84.02%. This study presents a general and viable approach for fabricating efficient ST-PSCs.

The dual-action reductant KBH₄ is employed to suppress the harmful reaction between NiO_x and perovskite while simultaneously avoiding iodide oxidation in perovskite. High-quality perovskite film with low-defect density on NiO_x@KBH₄ is achieved during the deposition in ambient conditions. This significantly improves the power conversion efficiency and stability of perovskite solar modules.

Abstract

Nickel oxide (NiO_x)-based inverted perovskite solar cells stand as promising candidates for advancing perovskite photovoltaics towards commercialization, leveraging their remarkable stability, scalability, and cost-effectiveness. However, the interfacial redox reaction between high-valence Ni⁴⁺ and perovskite, alongside the facile conversion of iodide in perovskite into I₂, significantly deteriorates the performance and reproducibility of NiO_x-based perovskite photovoltaics. Here, potassium borohydride (KBH₄) is introduced as a dual-action reductant, which effectively avoids the Ni⁴⁺/perovskite interface reaction and mitigates the iodide-to-I₂ oxidation within perovskite film. This synergistic redox modulation significantly suppresses nonradiative recombination and increases the carrier lifetime. As a result, an impressive power conversion efficiency of 24.17% for NiO_x-based perovskite solar cells is achieved, and a record efficiency of 20.2% for NiO_x-based perovskite solar modules fabricated under ambient conditions. Notably, when evaluated using the ISOS-L-2 standard protocol, the module retains 94% of its initial efficiency after 2000 h of continuous illumination under maximum power point at 65 °C in ambient air.

CuAlSe₂ is unstable and decomposes easily in air. Alloying with elemental In leads to a significant improvement in stability, and Cu(In,Al)Se₂ solar cells demonstrate greater photovoltaic performance than that of CuInSe₂ cells. The alkali effects and metastable phenomena observed for aluminum-based chalcopyrite films and devices provide important hints for elucidating the mechanisms behind these effects and phenomena in chalcopyrite solar cells.

Abstract

Aluminum-based chalcopyrite materials have attracted attention because of the wide controllability range of their material properties and potential for use in energy-conversion devices. Herein, CuAlSe₂-based thin-film growth and solar cell device properties are discussed. Ternary CuAlSe₂ thin films are relatively unstable and decompose weeks after film growth, even when preserved in a dry box. However, alloying with elemental In led to significant improvements in stability. Cu(In,Al)Se₂ (CIAS) solar cells yield better photovoltaic performance than CuInSe₂ cells, although the effective range of Al concentration that can improve device performance is narrower than that of elemental Ga in Cu(In,Ga)Se₂ (CIGS). A decrease in the alkali metal concentration in CIAS films with increasing Al concentration is observed, indicating that the formation energy of alkali-metal substitutional defects on the Cu site is high, and/or Al-related complex defects formed are kinetically stable and difficult to replace with alkali metals once they form. Although the direct observation of alkali metals in the bulk (grain interior) of chalcopyrite CuInSe₂ and CIGS films has been difficult to date, this result can serve as indirect evidence of the presence of alkali metals in the bulk of CuInSe₂ films.

By incorporating Hydantoin into the precursor, the crystallization kinetics of perovskite is effectively regulated, resulting in the formation of perovskite films with a highly-oriented out-of-plane orientation. This enhancement is accompanied by a significant reduction in defect density, leading to perovskite solar cells (PSCs) with a remarkable efficiency of 25.66% (certified 25.15%) and outstanding stability.

Abstract

Organic-inorganic hybrid perovskites have emerged as highly promising candidates for photovoltaic applications, owing to the exceptional optoelectronic properties and low cost. Nonetheless, the performance and stability of solar cells suffer from the defect states of perovskite films aroused by non-optically active phases and non-centralized crystal orientation. Herein, a versatile organic molecule, Hydantoin, to modulate the crystallization of perovskite, is developed. Benefiting from the diverse functional groups, more spatially oriented perovskite films with high crystallinity are formed. This enhancement is accompanied by a conspicuous reduction in defect density, yielding efficiency of 25.66% (certified 25.15%), with superb environmental stability. Notably, under the standard measurement conditions (ISOS-L-1I), the maximum power point (MPP) output maintains 96.8% of the initial efficiency for 1600 h and exhibits excellent ion migration suppression. The synergistic regulation of crystallization and spatial orientation offers novel avenues for propelling perovskite solar cell (PSC) development.

DTTP-ThSO is designed by dual-strategy method combining conjugate engineering and side chain engineering, which can construct six-membered ring through S⋅⋅⋅O noncovalent conformation lock. DTTP-ThSO exhibits high hole mobility, good energy level matching, and strong defect passivation ability. The dopant-free DTTP-ThSO-based PSCs achieve an impressive PCE of 23.3 % with an FF of 82.3 %, among the highest performance n-i-p PSCs with dopant-free HTMs.

Abstract

Dopant-free hole transport materials (HTMs) are ideal materials for highly efficient and stable n-i-p perovskite solar cells (PSCs), but most current design strategies for tailoring the molecular structures of HTMs are limited to single strategy. Herein, four HTMs based on dithienothiophenepyrrole (DTTP) core are devised through dual-strategy methods combining conjugate engineering and side chain engineering. DTTP-ThSO with ester alkyl chain that can form six-membered ring by the S⋅⋅⋅O noncovalent conformation lock with thiophene in the backbone shows good planarity, high-quality film, matching energy level and high hole mobility, as well as strong defect passivation ability. Consequently, a remarkable power conversion efficiency (PCE) of 23.3 % with a nice long-term stability is achieved by dopant-free DTTP-ThSO-based PSCs, representing one of the highest values for un-doped organic HTMs based PSCs. Especially, the fill factor (FF) of 82.3 % is the highest value for dopant-free small molecular HTMs-based n-i-p PSCs to date. Moreover, DTTP-ThSO-based devices have achieved an excellent PCE of 20.9 % in large-area (1.01 cm²) devices. This work clearly elucidates the structure-performance relationships of HTMs and offers a practical dual-strategy approach to designing dopant-free HTMs for high-performance PSCs.

Publication date: 1 June 2024

Source: Nano Energy, Volume 124

Author(s): Qian Zhou, Baibai Liu, Yu Chen, Danqing Ma, Xiao Han, Dongmei He, Zhengfu Zhang, Hua Yang, Pengjun Zhao, Juan Hou, Liming Ding, Jing Feng, Jianhong Yi, Jiangzhao Chen

Publication date: 1 June 2024

Source: Nano Energy, Volume 124

Author(s): Zhigang Che, Limeng Zhang, Jiacheng Shang, Yan Zhan, Yurong Zhou, Fengzhen Liu

Publication date: 1 June 2024

Source: Nano Energy, Volume 124

Author(s): Huan Li, Guanshui Xie, Jun Fang, Xin Wang, Sibo Li, Dongxu Lin, Daozeng Wang, Nuanshan Huang, Haichen Peng, Longbin Qiu

Publication date: 1 June 2024

Source: Nano Energy, Volume 124

Author(s): Bo Zhou, Pei Zhao, Junxue Guo, Yu Qiao, Shuaifeng Hu, Xin Guo, Jiewei Liu, Can Li

Publication date: 17 April 2024

Source: Joule, Volume 8, Issue 4

Author(s): Jieqiong Liu, Dexu Zheng, Kai Wang, Zhipeng Li, Shengzhong Liu, Lei Peng, Dong Yang

Publication date: 19 June 2024

Source: Joule, Volume 8, Issue 6

Author(s): Hesan Ziar

Publication date: 15 May 2024

Source: Joule, Volume 8, Issue 5

Author(s): Natalia Yantara, Nripan Mathews

The introduction of 2D perovskites, specifically using diethylammonium iodide as an ammonium salt, is explored as a strategy to enhance device performance and stability. Through spin coating DEAI onto the perovskite film surface, a 2D perovskite phase is formed, leading to increased hydrophobicity and improved humidity stability.

Interfacial passivation plays a pivotal role in achieving efficient and stable perovskite solar cells. Meanwhile, the introduction of 2D perovskites has also been widely reported to be beneficial for enhancing the performance and stability of devices. Herein, DEAI is used as an ammonium salt, which is spin coated onto the surface of the perovskite film, resulting in the formation of a 2D perovskite phase. This alteration increases the film's hydrophobicity, holding the promise of enhancing its humidity stability. Furthermore, DEAI effectively reduces trap density in the perovskite layer, suppressing nonradiative recombination and optimizing the surface potential, thereby improving the efficiency of devices. As a result, the inverted perovskite devices passivated with DEAI achieve a champion power conversion efficiency of 24.26%. Additionally, the unencapsulated DEAI-passivated perovskite solar cells demonstrate enhanced stability.