Research achievements and highlights

Optimization research on buried interfaces in perovskite solar cells,Professors Chen Wei and Liu Zonghao from Huazhong University of Science and TechnologyHand in HandShenzhen Vocational and Technical UniversityJingbai LiThe professor's team has made significant breakthroughs and delved into the topic of mixingSelf-assembled monolayer(SAMs)Mechanism of intermolecular interactions during sedimentationThis study was published in a top tier journal《Nature Communications》The title is《Modulating the competitive adsorption of hybrid self-assembled molecules for efficient wide-bandgap perovskite solar cells and tandems》.

The research team has developed a groundbreaking interface modification strategy, successfully solving the problem of wide bandgap perovskite solar cells(WBG PSCs)Mid - to long-term challenges - mixedSAMsInterface defects caused by competitive adsorption between them. Researchers systematically examined three different co adsorbents(PATheCAandSA)Compared to commonly usedSAMmaterialMe - 4PACzThe interaction mechanism and effectiveness impact between them.

The key achievements of the research include:

•Theoretical calculations revealSAKey role:Molecular Dynamics（MD）Simulation and Density Functional Theory（DFT）The calculation clearly indicates that,Co adsorbentSATend to fillNiOxandITOUncovered sites on the surfaceAnd withMe - 4PACzGenerate favorable interactions, promote their dispersion, and thus formDenser hole selection layer.SA-MeThe bonding energy is even higher thanMe-MeBonding energy helps to breakMe - 4PACzThe reunion.

•experimental verificationSAOptimize interface and perovskite quality:The experimental results strongly demonstrate that the use ofIn / me- 4 paczmixSAMsSignificantly reduced non radiative recombination losses at the interface and optimized the energy level arrangement of buried interfacesAnd effectively regulated itWBGThe crystalline quality of perovskite.XPSThe analysis further confirms thatSACan enhanceMe - 4PACzInNiOxAdsorption on top.SEMandXRDThe characterization techniques also showed that,SAThe introduction of improved perovskite thin filmsmorphologyAnd crystallinity.

•WBG PSCsSignificant improvement in efficiency:based onSAThe interface optimization strategy,1.77 eVWide bandgap perovskite solar cellsachieved20.67%Power conversion efficiency（PCE）And throughCertification achieved20.21%It is as high as1.332 VThe open circuit voltage（VOC），The authentication value is1.313 VIt performs outstandingly among similar devices. Compared to the control group, sedimentation inSAImproved perovskite thin films on substrates exhibithigherPLQYvalueAnd corresponding to higherQFLSvalue.

•All perovskite stacked devices have achieved near success29%Certification efficiency:Make this efficientWBG PSCsand1.26 eVNarrow energy gap（NBG）PSCsCombined, successfully preparedDouble ended perovskite stacked solar cell（TSCs）, itsPCEAchieve astonishing results28.94%(Certification value)28.78%, small area0.087 cm2）In addition,Small size module (aperture area)11.3 cm2) It has also been achieved23.92%ofPCE.

•Stacked devices exhibit excellent long-term stability:useSAImproved interface for fully perovskite stacked devices under harsh conditions（85 ℃，N2or 85 ℃/85%The relative humidity exhibits excellent long-term operational stability.

Figure 1i：SABroadband perovskite solar cells on substrate(WBG PSCs)The BestJ-Vcurve

research team

This groundbreaking research was jointly conducted by a cross disciplinary team, and the corresponding author isProfessor Chen Wei from Huazhong University of Science and Technology（Wei Chen）And Liu Zonghao（Zonghao Liu）Professor and Shenzhen Vocational and Technical UniversityJingbai Li教授。

This important research work mainly consists of the followingunitconduct:

1. Huazhong University of Science and Technology(Huazhong University of Science and Technology, HUST)

2. Shenzhen Vocational and Technical College(Shenzhen Polytechnic University)

3. Optics Valley Laboratory(Optics Valley Laboratory)

Research Background

•The complexity of interface engineering:Although self-assembled monolayers(SAMs)Widely used to improve the interface of perovskite solar cells, butmixSAMsInteraction and competitive adsorption behavior during sedimentation processNot yet fully researched. Understanding how co adsorbents affect commonSAMmaterial(asMe - 4PACzThe film-forming process is a challenge.

•Non radiative composite loss:WBG PSCsThe efficiency is limited byNon radiative recombination loss at the interfaceHow to effectively passivate interface defects, reduce charge recombination, and improve open circuit voltage(VOC)It is a key challenge.

•Realize high open circuit voltage(VOC)：althoughWBGThe material has the potential for highVOCHowever, the actual componentsVOCOften below the theoretical limit.reduceVOClossEspecially the losses related to non radiative recombination at the interface are the key to improving efficiency.

•Energy alignment issue:In the hole selection layer(HTL)Between the perovskite layerPoor energy alignmentIt will hinder charge transfer and reduce device efficiency.

•Crystallization quality of perovskite thin films:obtainHigh quality, uniform, and defect free wide bandgap perovskite thin filmsStill a challenge. Interface modifiers need to be able to effectively regulate the nucleation and growth process of perovskite.

•The development of all perovskite layered batteries:EfficientlyWBG PSCsCompared to narrow energy gaps(NBG) PSCsIntegrating to build high-performance all perovskite stacked cells requiresPrecise control of the interface between sub batteriesAnd ensure effective charge recombination.

Figure 3b

solution

The research team has proposed to address the difficulties and challenges mentioned aboveRegulating mixed self-assembled monolayers(SAMs)Competitive adsorption behaviorCore solutions and methods:

•Precise control interface formation:The research team conducts in-depth researchco-adsorbents(PA,CA,SA)Compared to commonly usedSAMmaterialMe-4PACzThe interaction between them. Through molecular dynamics(MD)Simulation and Density Functional Theory(DFT)Calculations reveal differentco-adsorbentsandMe - 4PACzInNiOxandITOSurface adsorption behavior and energy.

•Optimize hole selection layer:Research findsSAasco-adsorbentIt can effectively fill uncovered sites without interferingMe - 4PACzAdsorption ensures the formation of a dense hole selection layer.

•Inhibition of non radiative recombination:In / me- 4 paczmixSAMsCan effectively reduce non radiative recombination losses at the interfaceThis is achieved through higher photoluminescence quantum yield(PLQY)Splitting of quasi Fermi levels(QFLS)Worth verifying.

•Improve energy alignment:The calculation and experimental results indicate that,SA-MeDimerization can achieve better energy level alignmentIt helps to extract and transport electric holes from the perovskite layer to the transmission layer.

•Regulating the crystallization of perovskite:In-situ photoluminescence(PL)SpectrumXX-ray diffraction(XRD)And grazing incidence wide-angleXRay scattering(GIWAXS)According to the characterization,SAModified interfaces contribute to obtaining higher quality, better crystallinity, and fewer defects in wide bandgap perovskite films.

•Increase open circuit voltage(VOC)：Through the above strategies, significant improvements have been madeWBG PSCsofVOCAnd confirmed through energy loss analysisThe reduction of non radiative composite losses isVOCThe main reason for improvement.

•Building efficient stacked batteries:EfficientlySAmodificationWBG PSCsCompared to narrow energy gaps(NBG)PSCsCombined, successfully preparedhigh efficiency(28.94%Certification value28.78%)The fully perovskite stacked solar cellAnd demonstrate good stability.

By selecting the appropriate oneco-adsorbent(SA)andMe - 4PACz形成混合SAMsFine tuning of interface characteristics to comprehensively enhance the performance of wide bandgap perovskite solar cells and their applications in all perovskite stacked cells.

FigureS10

Experimental steps and process

material preparation

•The research mainly uses[4-(3,6-dimethyl-9H-carbazol-9-yl)butyl]phosphonic acid(Me-4PACz)As a self-assembled monolayer(SAM)Material Science.

•Simultaneously using three different bifunctional alkyl amines as co adsorbents:(6-aminohexyl)-phosphonic acid(PA)The7-aminoheptanoic acid(CA)and6-aminohexane-1-sulfonic acid(SA).

•These materials are dissolved in ethanol in a specific ratio to form a mixtureSAMsSolution.

•wide bandgap(WBG)The precursor solution for perovskite solar cells is based onFA0.8Cs0.2Pb(I0.6Br0.4)3The composition.

•Narrow energy gap(NBG)The precursor solution for perovskite solar cells is based onFA0.6MA0.3Cs0.1Pb0.5Sn0.5I3 The composition.

Research process and important findings

•Computational research(DFTsummationMDsimulation)：

○DFTcalculation:discussPATheCAandSAInNiOxandITOsurfaceThe combination mode and adsorption energy. The results show thatSAInITOThe adsorption energy on the surface is stronger thanMe - 4PACz.

○MDSimulation:Research on co adsorbents andMe - 4PACzCompetitive adsorption behavior.SACan be adsorbed firstNiOxOn the surface, then throughSA-MeDimeric reinforcementMe - 4PACzAdsorption helps to form a more uniform layer of adsorbed molecules and fill itNiOxInITOAreas not covered on the surface.SA-MeThe binding energy of dimer is greater thanMe-Medimer.

○Calculations show that,SA-MeDimerization can achieve better energy level alignment.

FigureS4a & Figure 1a-d

•Preparation and testing of solar cells:

○Based on different factorsSAMsmodifiedThis / NiOxThe substrate has been fully preparedWBG PSCsDevices.SAThe basic device has achieved the highest level ofPCE 20.67%(Certification value20.21%)andVoc 1.332 V(Certification value1.313 V).

○Optimized through integrationWBGandNBGSub battery, prepared2-End full perovskite stacked solar cell(TSCs)，based onSAThe stacked battery achieved the highestPCE 28.94%(Certification value28.78%).

○We also manufactured based onSAThe stacked micro components,averagePCEfor21.82±1.28%(Aperture area11.3 cm2).

Figure 4c

•Battery stability:

○based onSAThe stacked battery is85℃Neutralization of nitrogen atmosphere85℃/85%In environments with relative humidity, it exhibitsEnhanced storage stability. ContinuouslyAM 1.5 Gunder illuminationMPPTrun500After an hour,Maintained the initial statePCEof85%.

Figure 4f

Characterization of research results

Photoluminescence quantum yield(PLQY)Splitting of quasi Fermi levels(QFLS)

Measured the deposition of perovskite on different substratesPLQYAnd calculated the correspondingQFLSQuantifySAMs/Non radiative recombination losses at the perovskite interface.

image3d, eDisplay of perovskite thin films deposited on glass substratesPLQYvalue4.231%, corresponding toQFLSvalue1.388 eVFor sedimentation in mixed conditionsSAMsThe perovskite thin film on top,SAThe sample obtained the highestPLQYvalue3.005%, corresponding toQFLSvalue1.379 eV.SAThe co adsorption strategy can reduceSAMs/Non radiative recombination losses at the perovskite interface.

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current-voltage(J-V)curve

Measured based on different factorsSAMsmodifiedThis / NiOxWide bandgap for substrate preparation(WBG)Perovskite solar cells(PSCs)Stacked perovskite solar cells(TSCs)ofJ-VCurves, including forward and reverse scans.

l Wide bandgap perovskite solar cells(WBG PSCs)：useSAThe co adsorbent device demonstrated significant performance improvement, achieving the highest level of performancePCE 20.67%(Reverse scan) and1.332 VThe open circuit voltage(Voc)This result has been verified,PCEfor20.21%，Vocfor1.313 V(imageS23)These values were reported at the time(1.77 eV)WBG PSCsAt the top level.

l Full perovskite stacked solar cell(All-Perovskite TSCs)：SAThe co adsorbent also significantly improved the performance of the stacked battery, reaching the highest levelPCE 28.94%(Reverse scan) and2.146 VofVocStable power outputPCEfor28.72%(imageS37)The stacked battery'sPCEVerified as28.78%，Vocfor2.145 V(imageS38).

l based onSAStacked micro components:Based on five sub batteriesSAThe stacked micro components exhibit good uniformity, with an average ofPCEreach, achieve, attain21.82 ±1.28%(Aperture area11.3 cm2)The Best Micro ComponentsPCEfor23.92%，Vocfor10.10 V(image4e).

external quantum efficiency(EQE)

The research team usesEnlitech QE-RQuantum efficiency measurement systemMeasured based on different factorsSAMsThe Single SettlementWBG PSCsandNBG PSCsAnd the stacked solar cellsEQESpectrum.

imageS20: Control groupPAGroupCAgroup andSAgroupWBGdeviceEQEpointsJscrespectively 17.42、17.60、17.64and18.06 mA cm?2, withJ-VScanned and extractedJsccoincide. image4dAnd the pictureS36bdisplayedSAbaseTSCofWBGandNBGThe sub batteryEQESpectrum,EQEintegralWBGandNBGThe sub batteryJscThe values are respectively 15.94and15.71 mA cm?2.

In-situ photoluminescence(PL)spectrum

Monitoring the precursor spin coating and annealing stages of perovskite in the control group andSACrystallization behavior on the substrate. （imageS24）

XX-ray Photoelectron Spectroscopy(XPS)

useXPSMeasured based onMe - 4PACzIndividual (control group) and in combination withPATheCAorSAmixedSAMsmodifiedThis / NiOxThe surface chemical composition and elemental valence states of the substrate. Verify the existence of co adsorbents and study their effects onMe - 4PACzInNiOxThe influence of surface adsorption and conductivity.XPSThe results directly confirmed that the co adsorbent was mixedSAMsThe existence in and revelation ofSAThe introduction can not only effectivelyMe - 4PACzCo adsorption can also enhanceMe - 4PACzandNiOxCombining and improvingNiOxThe conductivity.（imageS9TheS10TheS11TheS12）

Dynamic Light Scattering(DLS)

useDLSThe particle size distribution of microgel particles in different mixed adsorption molecular solutions was measured. The results showed that the introduction of co adsorbents reducedMe - 4PACzThe average size of the micro gel particles formed in the solution indicates that the co adsorbent inhibitsMe - 4PACzFormation of micro colloidal particles（imageS13）

ultraviolet-visible light(UV-Vis)spectrum

monitorMe - 4PACzInThis / NiOxAdsorption kinetics on substrates for individualMe - 4PACzSolution andMe - 4PACzandPATheCAorSAThe mixed solution.In / me- 4 paczThe adsorption rate is faster and the loading capacity is higher.（imageS14）

Contact angle measurement

Measured water droplets in the control group andPATheCAandSAprocessedThis / NiOxContact angle on the substrate.The increase in contact angle indicates that the introduction of co adsorbents will increase the hydrophobicity of the surface, mainly due to mixingSAMsBetter coverageThis / NiOxOn the surface, the exposure of highly hydrophilic groups is reduced.（imageS15）

XX-ray diffraction(XRD)And grazing incidenceXX-ray diffraction(GIXRD)

useXRDMeasured sedimentation in different areasSAMsThe crystal structure of perovskite thin films on modified substrates. useGIXRDStudied the residual stress of thin films. （imageS26、imageS27）

Grazing incidence wide-angleXRay scattering(GIWAXS)andPLmapping

Expose the bottom surface of perovskite using exfoliation technique and performGIWAXSandPLMapping representation. Research on MixingSAMsThe impact on the quality of perovskite at the bottom interface and non radiative recombination. Compared to the control group,SAPerovskite based thin films exhibit higher performancePLStrength and uniformity indicate that non radiative recombination at the bottom interface is suppressed. （imageS28, picture2i-l）

Ultraviolet photoelectron spectroscopy(UPS)

Measure the prepared hole transport layer(HTL)The arrangement of energy levels. evaluateSAMsDecorate forThis / NiOxMaximum value of work function and valence band(VBM)The impact. （image3aAnd the pictureS29）

Time-resolved photoluminescence(TRPL)

Measure sedimentation in different areasSAMsCarrier dynamics of perovskite thin films on modified substrates. （image3b, c）

Conclusion

The research team delved into the in-depth exploration of mixed self-assembled monolayers(SAMs)CCP Adsorbents and[4-(3,6-Dimethyl-9H-carbazole-9-base)butyl]Phosphonic acidMe-4PACzThe interaction between perovskite solar cells and their application in high-efficiency wide bandgap perovskite solar cells(WBG PSCs)Applications in stacked solar cells. Research finds that6-Aminohexane-1-sulfonic acid(SA)As a co adsorbent, it can effectively fill uncovered sites without interferingMe - 4PACzThe adsorption results in the formation of a dense layer of hole selection.

Through molecular dynamics(MD)Simulation and Density Functional Theory(DFT)Calculation and research have elucidatedSAandMe - 4PACzThe balanced surface and intermolecular interactions between molecules contribute toMe - 4PACzInNiOxandITOMore uniform adsorption on the surface.XPSThe characterization results further validatedSAIn the mixSAMsExistence in and displaySAcanenhanceMe - 4PACzandNiOxThe ability to combine and improveNiOxThe conductivity.

The main achievements of this study include:

• Based onIn / me- 4 paczmixSAMsof1.77 eV WBG PSCsAchieved up to20.67%Power conversion efficiency(Verified as20.21%)and1.332 VThe open circuit voltage(Verified as1.313 V).

•In / me- 4 paczmixSAMsEffectively reduced non radiative recombination losses at the interface, optimized energy level arrangement, and regulatedWBGCrystallization of Perovskite.XRDandSEMAccording to the characterization results, useSAThe perovskite thin film deposited on the substrate hasHigher crystallinity, fewer defects, and smoother surface.

• Optimize theWBGSecondary batteries and1.26 eVNarrow energy gap(NBG) PSCCombined, preparedFull perovskite stacked solar cell(TSCs), itsPCEreached28.94% (Verified as28.78%)，Vocfor2.146 V.

• Based onSAStacked micro components (aperture area)11.3 cm2）Showing an average21.82%ofPCEThe Best DevicePCEreach, achieve, attain23.92%，Vocfor10.10 V.

Stability testing shows that based onSAStacked devices under continuous illumination500Can still maintain its initial state even after hoursPCEof85%At the same time, it also exhibits enhanced performance in terms of thermal stability and wet heat stability.

Reference from Nature Communications_SOI: 10.1038/s41467-025-5811-y

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