Tailoring the mercaptan ligands for high performance inverted perovskite solar cells with efficiency exceeding 21%

Interface passivation engineering has been recognized as an effective way to simultaneously contribute to the optoelectronic characteristic and stability of perovskite solar cells(PSCs). Herein, a p-conjugated dual-ligand 1,4-phenylmercaptan(PHMT) is explored to rationally tailor the surface of perovskite film.The experimental and theoretical results show that the PHMT presents planar structure and obvious electron delocalization characteristics, which allow it to anchor on the surface of perovskite with a certain orientation, thereby promoting the transport of interface charge. Moreover, the two sulfhydryl groups in PHMT reduce the trap density of the perovskite film by passivating under-coordinated lead ions.Consequently, the PHMT-modified inverted device based on MAPbI_(3)(MA: methylammonium) achieves enhanced efficiency from 18.11%(control) to 21.11%, along with the ambient stability up to 3500 h.After being placed at 85 °C for 500 h or illuminated for 600 h, the modified device remains over 89%or 86% of initial efficiency. This discovery opens a new window for the choice of passivators to improve the performance of PSCs.

Gadolinium-incorporated CsPbI_(2)Br for boosting efficiency and long-term stability of all-inorganic perovskite solar cells

All-inorganic CsPbI_(2)Br perovskite solar cells(PSCs)have received extensive research interests recently.Nevertheless,their low efficiency and poor long-term stability are still obstacles for further commercial application.Herein,we demonstrate that high efficiency and exceptional long-term stability are realized by incorporating gadolinium(III)chloride(GdCl_(3))into the CsPbI_(2)Br perovskite film.The incorporation of GdCl_(3) enhances the Goldschmidt tolerance factor of CsPbI_(2)Br perovskite,yielding a dense perovskite film with small grains,thus the a-phase CsPbI_(2)Br is remarkably stabilized.Additionally,it is found that the GdCl_(3)-incorporated perovskite film achieves suppressed charge recombination and appropriate energy level alignment compared with the pristine CsPbI_(2)Br film.The noticeable increment in efficiency from14.01%(control PSC)to 16.24%is achieved for GdCl_(3)-incorporated PSC.Moreover,the nonencapsulated GdCl_(3)-incorporated PSC exhibits excellent environmental and thermal stability,remaining over 91%or90%of the original efficiency after 1200 h aging at 40%relative humidity or 480 h heating at 85℃ in nitrogen glove box respectively.The encapsulated GdCl_(3)-incorporated PSC presents an improved operational stability with over 88%of initial efficiency under maximum power point(MPP)tracking at 45℃ for1000 h.This work presents an effective ion-incorporation approach for boosting efficiency and long-term stability of all-inorganic PSCs.

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 I2release 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.

Surface modification with ionic liquid for efficient CsPbI2Br perovskite solar cells

The presence of numerous trap states on the perovskite surface severely affects the performance of inorganic CsPbI_(2)Br perovskite solar cells.Surface modification has been proven to be an effective strategy to passivate the surface trap states of CsPbI_(2)Br perovskite.However,most modifiers behave high volatility and insulation,not enough to further develop the CsPbI_(2)Br solar cells.Herein,an ionic liquid of 1-viny-3-propionate ethyl imidazolium chloride([PEVIM]Cl)is applied to modify the CsPbI_(2)Br film surface,yielding a compact film with enhanced crystallinity.The surface trap states of CsPbI_(2)Br film are effectively passivated via the interaction between carbonyl group of[PEVIM]Cl and uncoordinated metal cations of CsPbI_(2)Br perovskite,leading to charge recombination suppression and charge transport enhancement.Consequently,the power conversion efficiency(PCE)of[PEVIM]Cl modified CsPbI_(2)Br device is obviously enhanced from 12.49% to 14.19% with an improved open-circuit voltage of 1.160 V.Moreover,the non-encapsulated device presents excellent thermal stability,still maintaining 91%PCE when heated at 85℃ in nitrogen atmosphere for 360 h.Meanwhile,the non-encapsulated device degrades only 11% PCE after stored at 50% relative humidity for 960 h.This simple and efficient approach provides a promising direction to fabricate high-efficiency and stable inorganic perovskite devices.

In-MOF-derived In_(2)S_(3)/Bi_(2)S_(3) heterojunction for enhanced photocatalytic hydrogen production

Transition metal sulfides are commonly studied as photocatalysts for water splitting in solar-to-fuel conversion.However,the effectiveness of these photoca-talysts is limited by the recombination and restricted light absorption capacity of carriers.In this paper,a broad spectrum responsive In_(2)S_(3)/Bi_(2)S_(3)heterojunction is cons-tructed by in-situ integrating Bi_(2)S_(3)with the In_(2)S_(3),derived from an In-MOF precursor,via the high-temperature sulfidation and solvothermal methods.Benefiting from the synergistic effect of wide-spectrum response,effective charge separation and transfer,and strong heterogeneous interfacial contacts,the In_(2)S_(3)/Bi_(2)S_(3)heterojunction demons-trates a rate of 0.71 mmol/(g∙h),which is 2.2 and 1.7 times as much as those of In_(2)S_(3)(0.32 mmol/(g∙h))and Bi_(2)S_(3)(0.41 mmol/(g∙h)),respectively.This paper provides a novel idea for rationally designing innovative heterojunc-tion photocatalysts of transition metal sulfides for photocatalytic hydrogen production.

Multidentate anchoring through additive engineering for highly efficient Sb_(2)S_(3)planar thin film solar cells

Sb_(2)S_(3)is a promising candidate for the flexible solar cells or the top subcells in tandem solar cells due to its wide-bandgap,less toxic,acceptable cost and progressive power conversion efficiency(PCE).However,the poor quality and high trap states of Sb_(2)S_(3)films limit the device performance further enhancement.Herein,we adopt a multidentate ionic liquid,tetramethylammonium hexafluorophosphate([TMA][PF_(6)])as a novel additive to address this issue.The octahedral[PF_(6)]~-contains six different oriented fluorine atoms with the lone pair electrons,which could coordinate with Sb atoms due to the multidentate anchoring.Thus,the high-quality Sb_(2)S_(3)film with low trap states has been achieved.Moreover,the Fermi level of the Sb_(2)S_(3)film has been upshifted,thereby showing an effective charge transfer.As a result,all photovoltaic parameters of the optimized Sb_(2)S_(3)devices are obviously enhanced,boosting the final PCE from 4.43(control device)to 6.83%.Our study about the multidentate anchoring is manifested to be an effective method to enhance the Sb_(2)S_(3)device performance.

Effective additive for enhancing the performance of Sb_(2)S_(3) planar thin film solar cells

Sb_(2)S_(3) is a promising photovoltaic absorber with appropriate bandgap,excellent light absorption coefficient and great stability.However,the power conversion efficiency(PCE)of Sb_(2)S_(3) planar thin film solar cells is unsatisfactory for further commercial application due to low crystallinity and high resistivity of Sb_(2)S_(3) film.Here,we introduce an additive of 4-Chloro-3-nitrobenzenesulfonyl Chloride(CSCl)to alleviate these problems.The CSCl molecular contains two terminal Cl with lone pair electrons,which have the interaction with Sb atoms.Thus,the Sb_(2)S_(3) film with enhanced crystallization and low trap states has been obtained and the resistivity is also decreased.Furthermore,CSCl additive raises the Fermi level of the Sb_(2)S_(3) film,thereby enhancing the transport of electron from Sb_(2)S_(3) to TiO_(2).Consequently,the optimal PCE of Sb_(2)S_(3) solar cells is raised from 4.20%(control device)to 5.84%.Our research demonstrates a novel additive to enhance the photoelectric performance of Sb_(2)S_(3) solar cells.