To achieve high-efficiency photocatalytic H2O2 production, it is essential to modulate the charge-carrier lifetime of the photocatalyst. Herein, a series of xAg-ZnO/TiO2 (x = 0, 20, 30, 40 mg AgNO3) materials are synthesized by pyrolysing Ag-doped ZnTi-LDH. Among these, compared with pristine ZnTi-LDH, the 30Ag-ZnO/TiO2 sample shows a 113.7-fold higher photocatalytic H2O2 generation rate, reaching 4.6 mmol g−1 h−1. Meanwhile, Ag-ZnO/TiO2 retains the two-dimensional morphology of ZnTi-LDH, and a 9.8-fold increase in specific surface area is observed for 30Ag-ZnO/TiO2 relative to pristine ZnTi-LDH. The presence of Ag optimises charge distribution and introduces impurity levels near the Fermi level, narrowing the bandgap. Concurrently, the ZnO/TiO2 heterojunction further accelerates carrier separation and migration, enabling highly efficient photocatalytic H2O2 production. Furthermore, the photocatalytic mechanism of two-step single-electron ORR (O2 → •O2− → H2O2) is confirmed via XPS, EPR and DFT. This research can act as a reference for the fabrication of heterojunctions through metal doping and in-situ derivation, as well as practical guidance for the green synthesis of H2O2.

Indium tin oxide (ITO) serves as the window layer material in Cu2ZnSn(S,Se)(4) (CZTSSe) solar cells, where its optical transparency and electrical conductivity critically determine both light absorption capacity and charge collection efficiency. Although crystalline ITO exhibits superior optoelectronic properties, conventional thermal annealing methods often lead to the degradation of other functional layers, limiting the use of ITO to amorphous or low-crystallinity states. This study proposes a laser scanning strategy to induce in-situ crystallization of ITO. Leveraging the rapid and controllable heating characteristics of laser processing, the sheet resistance of the ZnO/ITO stack is reduced from 24.4 Omega/square to 10.3 Omega/square (a 58% decrease), significantly enhancing lateral conductivity and carrier collection efficiency toward electrodes. Meanwhile, transmittance measurements on the CdS/ZnO/ITO stack reveal a similar to 10% improvement in the 400-1100 nm wavelength range, allowing more visible light to reach the space charge region and thereby increasing solar energy utilization. Additionally, laser-induced thermal effects improve the crystallinity and reduce the sheet resistance of the ITO window layer, thereby enhancing charge collection and contributing to an impressive increase of 5 mA/cm(2) in the short-circuit current density of the CZTSSe solar cell. Further analysis identifies a laser-induced graded Cd distribution near the CZTSSe/CdS interface, demonstrating that laser annealing provides an effective approach for controllable gradient elemental doping. These synergistic improvements in both electrical and optical performance of the window layer collectively contribute to the notable device performance advancement.

Substantial defects within the absorber layer and at the front interface of Cu2ZnSn(S, Se)4 (CZTSSe) solar cells have been identified as the primary factor limiting further performance enhancement. This study systematically investigated the correlation between device performance and defect properties (type, capture cross section (sigma), energy level (Et), and concentration (Nt)) in both the absorber layer and front interface. Our findings reveal that photovoltaic performance significantly depends not only on defect localization and fundamental parameters (sigma, Et, Nt) but also critically on defect type. When acceptor defects dominate the front interface, the device performance remains substantially inferior to that of systems with neutral or donor defects, regardless of other defect parameter variations, primarily attributed to severe open-circuit voltage (VOC) and short-circuit current density (JSC) degradation. Conversely, donor defects in the absorber layer coupled with Nt variations at both interfaces and in the absorber lead to diminished performance compared to neutral or acceptor defects, mainly through VOC and fill factor (FF) deterioration. Notably, the performance responses to alterations in sigma and Et demonstrate minimal dependence on the absorber layer defect type. This mechanistic understanding establishes a theoretical foundation for implementing experimental strategies to mitigate defect-induced performance losses in CZTSSe photovoltaics.

Kesterite Cu2ZnSn(S,Se)4 (CZTSSe) solar cells have emerged as a promising thin-film photovoltaic technology due to their earth-abundant and environmentally benign constituents, yet their performance is limited by a substantial open-circuit voltage deficit (VOC,def). This loss stems from bulk issues, including severe cation disorder and band tailing, coupled with interfacial problems such as non-ideal band alignment at the heterojunction interface (HEI). This study reports an effective Al-doping strategy to concurrently tackle these challenges in solution-processed Ag-alloyed CZTSSe (CAZTSSe) absorbers. Comprehensive characterization reveals that Al3+ ions preferentially occupy Zn2+ sites. This crucial substitution efficiently inhibits the formation of detrimental CuZn and [2CuZn+ SnZn] defect complexes, leading to a reduction in band tailing and non-radiative recombination losses, as indicated by a significant reduction in Urbach energy. Simultaneously, it induces favorable band bending and enhances the built-in potential within HEI, thereby improving charge carrier collection efficiency, as directly evidenced by prolonged carrier lifetimes and accelerated charge extraction in transient photocurrent/ photovoltage measurements. Consequently, the synergistic passivation of both bulk and interface yields a champion device with an efficiency of 13.60% and a reduced VOC,def of 0.36 V, ranking among the highest reported for IIIA-doped kesterite solar cells. Notably, the in-situ formed Al(Se,O)x passivation layer confers exceptional ambient stability, with the champion device retaining its initial performance after 1700 h. This work establishes Al-doping as a simple yet multifaceted strategy for defect control and interfacial engineering, offering a promising pathway toward high-performance, durable kesterite photovoltaics.

We discover a conceptually novel "back-to-front" diffusion-mediated passivation mechanism that unlocks a high open-circuit voltage (V-OC) of 0.57 V in kesterite solar cells, achieved by integrating Ag-doping with an ultrathin Al2O3 modification layer (Al2O3-ML) at the back electrode interface (BEI). Beyond their individual roles, i.e., Ag-doping suppresses Cu-Zn antisite defects while the Al2O3-ML inhibits interfacial reactions, a profound synergistic passivation effects (SPEs) emerges. The Al2O3-ML not only acts as a diffusion barrier to promote uniform Ag incorporation but also, unexpectedly, serves as an in-situ Al source. Al undergoes long-range diffusion to the front surface, forming an Al(Se,O)(x) passivation layer that effectively mitigates Fermi-level pinning by passivating interface trap states, which has been directly evidenced by a 0.6 eV positive shift in Al 2p X-ray photoelectron spectroscopy and a 0.13 eV upward shift of the Fermi level toward the valence band maximum. This bulk-to-interface engineering results in markedly improved absorber crystallinity, elemental homogeneity, and suppressed non-radiative recombination. Consequently, the champion device achieves a compelling 14.05% efficiency with a notably low open-circuit voltage deficit (V-OC,V-def) of 0.33 V and exceptional long-term stability (>5300 h), ranking among the best for Cu2ZnSn(S,Se)(4) (CZTSSe) devices employing BEI modification. This work establishes a new design paradigm, i.e., engineering the BEI to enable remote passivation of the critical front interface, which offers a broadly applicable strategy for emerging thin-film photovoltaics.

Low open-circuit voltage (V-OC) and fill factor (FF) remain key limitations to the efficiency of Cu2ZnSn (S, Se)(4) (CZTSSe) solar cells. In this work, three kinds of Ag/Cd co-doped CZTSSe (ACZCTSSe) solar cells, namely Cell-DMSO, Cell-MOE and Cell-MDM, were fabricated using monolayer precursor of ACZCTS-DMSO and ACZCTS-MOE as well as multilayer precursor with an ACZCTS-MOE/ACZCTS-DMSO/ACZCTS-MOE sandwich structure, respectively. The ACZCTS-MOE and ACZCTS-DMSO films were prepared via MOE and DMSO based solutions with different metal ion valence states, respectively. Cell-MDM achieved a champion efficiency of 14.52%, far exceeding that of the single-solvent devices Cell-DMSO (11.27%) and Cell-MOE (12.21%). It is demonstrated that the multilayer precursor not only increases V-OC and FF, but also enhances J(SC) in comparison with the two monolayer precursors. The increase in V-OC and FF is dominantly due to decrease in reverse saturation current density (J(0)), while increased Jsc to photogenerated current density (J(L)). The decrease in J(0) is mainly due to that the tail state density and [2Cu(Zn) + Sn-Zn] defect density of absorber of Cell-MDM is smaller than that of Cell-MOE and Cell-DMSO. The increased J(L) is mainly attributed to the fact that Cell-MDM exhibits a higher absorption coefficient, a wider depletion layer width, a stronger built-in electric field, and a smaller bandgap compared with Cell-MOE and Cell-DMSO.

In this study, MgF2 anti-reflection coatings (ARCs) with different thicknesses were deposited on the surface of Indium Tin Oxide (ITO) located between Ag electrodes of a CZTSSe solar cell by vacuum evaporation deposition. The thickness of the MgF(2 )ARC was controlled by varying its weight in the range of 0.01-0.04 g of MgF2. By optimizing the weight, the power conversion efficiency (PCE) of the CZTSSe solar cell increased from 10.40% without MgF2 ARC to 12.21% with MgF2 ARC produced with 0.02 g of MgF2. It was found that the increased PCE stems not only from an increase in short-circuit current density (J(SC)) but also from fill factor (FF). This is different from the previously reported literature results, where the increased PCE was usually attributed to an enhancement in J(SC). By calculating the percentage contribution of photogenerated current density (J(L)) and electrical parameters to J(SC) and FF, it was demonstrated that the increased J(SC) is mainly attributed to an increase in J(L), and the increased FF is attributed to a decrease in series resistance (Rs), reverse saturation current density (J0), and ideality factor of diode (A). The increase in J(L) results from the reduction of incident light loss by the anti-reflection effect of MgF2, the decrease in Rs from a decrease in resistivity of ITO caused by diffusion of F from MgF2 into ITO, and the decrease in A and J0 from a slight increase in carrier recombination due to Mg diffusion into ITO and a significant reduction in interfacial recombination because the device was annealed during thermal evaporation of MgF2.

It is known that lower fill factor (FF) and open-circuit voltage (VOC) are major obstacles limiting power conversion efficiency (PCE) of Cu2ZnSn (S,Se)4 (CZTSSe) solar cells. To resolve this problem, we proposed a novel strategy to fabricate a CZTSSe solar cell with conventional structure (Cell-DM) using a bilayer of CZTS precursor film (CZTS-DM). The bottom sublayer in the CZTS-DM was fabricated using CZTS precursor solution prepared with DMSO solvent and Cu+, Zn2+ and Sn2+ salts (DMSO-Sn2+), while the upper sublayer using CZTS precursor solution prepared with MOE solvent and Cu+, Zn2+ and Sn4+ salts (MOE-Sn4+). The highest PCE of Cell-DM reaches to 12.68%, larger than 10.70% of CZTSSe solar cell prepared using single layer CZTS precursor prepared with MOE-Sn4+ (Cell-MOE) and 10.17% of CZTSSe solar cell fabricated using single layer CZTS prepared with DMSO-Sn2+ (Cell-DMSO). The enhancement in PCE from Cell-MOE or Cell-DSMO to Cell-DM is attributed to increase in VOC and FF. The increase in VOC and FF is dominantly due to decrease in reverse saturation current density (J0) of the Cell-DM compared with Cell-MOE and Cell-DMSO, which is demonstrated to be ascribed to reduction in interfacial defects of Cell-DM. Interestingly, it is found that a graded bandgap (Eg) forms in the CZTSSe layer of Cell-DM, due to S/Se ratio in the CZTSSe decreases from back surface to front one. The graded Eg increases carrier separation ability and collection efficiency. This work provides a novel approach to reducing interfacial defects and constructing a graded bandgap in CZTSSe cells.

As an emerging photovoltaic technology, Cu2ZnSn(S,Se)4 (CZTSSe) thin-film solar cells are regarded as a viable, cost-effective alternative to satisfy future demand for green energy. This promise is attributed to their tunable bandgap (1.0~1.5 eV), high absorption coefficient (>104 cm-1), and environmentally friendly composition. Currently, the record power conversion efficiency (PCE) of CZTSSe devices has reached 16.6%, approaching commercial levels. However, this value remains significantly lower than its theoretical limit of 32.8% and the 23.6% achieved by the homologous CIGS technology, indicating immense potential for performance enhancement. The severe open-circuit voltage deficit (Eg/q-Voc) remains a critical factor preventing CZTSSe solar cells from reaching their expected efficiency. This issue is primarily associated with band misalignment and deep-level defects at the interfaces. At present, interface engineering has been demonstrated to be an effective strategy to significantly improve the performance of CZTSSe thin-film solar cells. Herein, we review the development process of CZTSSe photovoltaics, systematically discuss existing interface-related issues and comprehensively summarize recent strategies in interface engineering. Finally, to further elucidate the intrinsic mechanisms and facilitate the development of high-efficiency devices, future research directions and perspectives regarding interface engineering are proposed.

In the present work, two types of Cu2ZnSn(S, Se)4 (CZTSSe) solar cells, namely cell-MOE (MOE refers to 2-methoxyethanol) and cell-DMSO (DMSO refers to dimethyl sulfoxide), were fabricated using two Cu2ZnSnS4 (CZTS) precursor solutions: one employing MOE solvent and Sn4+ salt (MOE-Sn4+), and the other using DMSO solvent and Sn2+ (DMSO-Sn2+). Effects of the solvent types and the valence state of Sn on power conversion efficiency (PCE) of CZTSSe solar cell were investigated. It is found that the PCE of CZTSSe solar cells prepared with solution MOE-Sn4+ is higher than that of those prepared with solution DMSO-Sn2+. The highest PCE reaches 10.17% for cell-DMSO and 11.25% for cell-MOE. The advantage of MOE-Sn4+ solution is attributed to the fact that CZTS precursor film prepared with MOE-Sn4+ (CZTS-MOE) possesses a looser crystal structure and smaller grain size than that prepared with DMSO-Sn2+ (CZTS-DMSO). These structural and grain characteristics enable the CZTSSe derived from the selenization of CZTS-MOE (CZTSSe-MOE) to exhibit superior crystallinity compared with the CZTSSe obtained via the selenization of CZTS-DMSO (CZTSSe-DMSO). This enables CZTSSe-MOE to have a lower hole concentration, fewer band tail states, lower bulk and surface deep-level defect densities, and a reduced content of the Zn(S, Se) compared with CZTSSe-DMSO. These characteristics in turn endow cell-MOE with a wider depletion region width, stronger light absorption capacity, and less carrier recombination than cell-DMSO, thereby contributing to a higher photogenerated current density and a lower reverse saturation current density in cell-MOE relative to cell-DMSO.

Exploring superhard materials is of great significance in materials research. Ternary B-C-N superhard compounds exhibit a superior thermal stability to diamond, with hardness surpassing cubic boron nitride. However, synthesizing cubic B-C-N compounds is challenging, and few studies have been reported on their high-temperature oxidation resistance, impeding their potential applications. In this study, cubic B-C-N compounds (c-BCN) were synthesized using the high-pressure high-temperature synthesis method at 10 GPa and 1530 °C, half the reported pressure and one-quarter lower than the reported temperature. The thermal stability of the obtained c-BCN compound was examined. The results indicated that the air oxidation temperature of c-BCN was as high as 1200 °C, suitable for high-speed cutting of hardened steels. This study provided a production method of cubic B-C-N superhard compounds and extended their potential applications to milling/machining.

As is well-known, the lower open-circuit voltage (V OC) and fill factor (FF) are two major reasons for the lower efficiency of Cu2ZnSn(S,Se)(4 )(CZTSSe) solar cells. K-doping has become an effective means of improving the efficiency. In this work, the effect of K-doping on power conversion efficiency (PCE) was studied in a K-doping concentration (K/Cu) of 0 to 15 mol % at a selenization temperature ranging from 490 to 530 degrees C. As a result of our study, it was found that the optimal K-doping concentration for obtaining the highest PCE decreases with increasing selenization temperature. Through optimizing the K-doping concentration and selenization temperature, the highest PCE of 10.15% is obtained at K/Cu = 10 mol % and 510 degrees C. It is proved that the increased PCE induced by K-doping at a fixed selenization comes mainly from the decreased reverse saturated current density (J 0), then from the photogenerated current density (J(L)), series resistance (R-S), and shunt resistance (R-Sh).

The impeded transport of charge carriers presents a significant challenge that limits the open-circuit voltage (VOC) and efficiency of Cu2ZnSn(S,Se)4 (CZTSSe) solar cells, particularly within the absorber bulk and the back electrode interface (BEI). To address this issue, we have developed a dual optimization strategy that incorporates Ag-doping and Nb-engineering. This strategy offers two primary advantages: (i) Ag-doping enhances the crystallinity of the absorber while reducing bandgap fluctuations and suppressing the formation of CuZn antisite defects and band tailing; (ii) Nb-engineering induces a field passivation effect (NI-FPE) at the BEI, specifically in the p+-MoSe2:Nb/p--(Cu,Ag)2ZnSn(S,Se)4 (CAZTSSe) configuration. Moreover, this approach generates a synergistic passivation effect (SPE) between the BEI and the heterojunction interface (HEI), leading to an enhanced built-in potential, an expanded depletion region, and a reduced free carrier density due to the decreased carrier concentration in CAZTSSe as a result of Ag-doping. Consequently, recombination within the absorber bulk, BEI, and HEI has been effectively suppressed. By fine-tuning this strategy, we achieved a champion device with an impressive VOC of 529.87 mV and an efficiency of 12.56 %, representing a 69 % relative increase from the baseline efficiency of 7.44 %. This performance significantly exceeds that of devices utilizing only Ag-doping (9.51 %) or Nb-engineering (9.57 %). These findings highlight the potential of simultaneous optimization of the absorber and BEI to advance CZTSSe photovoltaic technology.

Enhancing the quality of the absorption layer represents a major approach to improving the optical response and electronic transport characteristics of Cu2ZnSn(S,Se)4(CZTSSe) solar cells. Numerous studies indicate that cation doping is a productive strategy for enhancement of efficiency. In this context, we present a method to enhance the crystallinity of the absorption layer and to passivate deep traps by doping Sr2+ into the absorption layer to partially replace Zn2+. The results demonstrate that Sr doping concentration of 0.10 yields the most significant improvement in film crystallinity. Concurrently, the density of beneficial defect clusters [VCu + ZnCu] increases, while that of harmful defect clusters [2CuZn + SnZn] decreases. At the same time, Sr doping can efficiently alleviate the band tailing phenomenon in the CZTSSe absorber layer and improve the open − circuit voltage (Voc). Upon the execution of the Sr doping strategy, the efficiency of Cu2SrxZn(1-x)Sn(S,Se)4(CSZTSSe)(0 ≤ x ≤ 0.2) solar cells increases from 6.31 % to 8.07 %, with the main contributing factors being the improvements in Voc and Fill Factor (FF). The proposed innovative methodology provides a comprehensive understanding of crystallization processes in kesterite-based solar cell materials, thereby paving the way for optimizing crystallinity and enhancing light-absorbing layer performance.

This paper introduces a spectral method based on free triangular meshes, termed the mesh based improved plane wave expansion method (MIPWEM), aimed at simplifying the design and analysis of phononic crystals (PnCs) in complex scenarios. This method, built upon the improved plane wave expansion method (IPWEM) theoretical framework, incorporates free triangular meshes to approximate various complex geometries, significantly reducing the derivation costs associated with handling complex inclusions. By varying factors such as the number of plane waves and mesh generation, this paper investigates the computational efficiency of the proposed MIPWEM from different perspectives. Additionally, the method is successfully applied to compute cases with complex geometries. These results further validate the advantages of the new method in handling complex geometries, computational speed, and other aspects. The MIPWEM with superior efficiency, shows great potential for PnCs research in multiphysics and high-frequency applications.

It is well known that the improvement of crystal quality and photoelectric properties of Cu2ZnSn(S,Se)4 (CZTSSe) is one of the key issues in enhancing power conversion efficiency (PCE). To resolve this problem, we selected Li2CO3 as a lithium source to prepare Li-doped CZTSSe by air annealing Li-doped Cu2ZnSnS4 (CZTS) precursor films in air, followed by selenization (denoted as CZTSSe-Li-A). It is interesting that the air annealing facilitates the incorporation of Li and O into CZTSSe as Li-O pairs. This pairing improves the crystal quality and absorption coefficient of CZTSSe-Li-A while reducing its hole concentration and resistivity compared to non-air-annealed Li-doped CZTSSe (CZTSSe-Li). By optimizing the Li doping concentration, annealing temperature and time, the highest PCE of the CZTSSe-Li-A solar cell (without the MgF2 anti-reflection layer) reaches 11.13%, which is larger than the highest PCE of the CZTSSe-Li solar cell (10.21%). Quantitative analysis indicates that the increased PCE of the CZTSSe-Li-A solar cell compared to the CZTSSe-Li solar cell is mainly attributed to the decrease in reverse saturation current density (J0) and series resistance (Rs) caused by the thermal effect of the air annealing, followed by an increase in photogeneration density (JL) and shunt resistance (Rsh). The decreased J0 stems from a reduction in interfacial defect density, the increased JL results from an increase in light absorption (alpha) and the depletion region width, and the decreased Rs and increased Rsh are ascribed to improved crystal quality. This work offers a route for the improvement of PCE of CZTSSe solar cells.

Tungsten diselenide (WSe2) has emerged as a highly promising material for lithium/sodium-ion batteries due to its exceptional electrical and chemical properties and unique sandwich-like two-dimensional structures. In this work, we present a chemical vapor deposition approach for synthesizing densely packed vertically oriented 2H-phase WSe2 nanosheets uniformly grown on tungsten foil. As an electrode material, the as-synthesized WSe2 exhibits remarkable electrochemical performance including excellent cycling stability, high-rate capability, and superior electrochemical activity. The WSe2 nanosheets demonstrate a high reversible specific capacity of 159.3 mAh g-1 at a current density of 5 A g-1, maintaining a near-100% Coulombic efficiency over 2400 cycles. The underlying mechanism governing electrochemical performance was further investigated using first-principles density functional theory computations. These findings underscore the potential of WSe2 nanosheets as high-performance materials for next-generation LIBs.

Cu2ZnSn (S, Se)4 (CZTSSe) semiconductors have become a recent focus of research owing to their costeffectiveness, environmental friendliness, and high efficiency. However, insufficient band alignment between the CZTSSe absorption layer and the CdS buffer layer significantly hampers the high conversion efficiency of CZTSSe devices. In this study, problems related to energy-band matching were solved by the post-heat treatment (PHT) of the absorber and buffer layers. Based on obtaining a high-quality absorption layer through doubledoped (Cu, Ag)2Zn(Sn, Sb)(S, Se)4 (CAZTSSSe), the impact of the PHT process of CAZTSSSe/CdS on the device performance and heterojunction quality was investigated. The PHT process promoted the reciprocating motion of elements in the heterojunction region, directly inducing the movement of Cd towards the absorption layer and Cu towards the buffer layer. Furthermore, the PHT method enhances the recrystallization of CdS, resulting in the formation of a CdS layer with excellent crystalline quality. After PHT processing, a more favorable conduction band arrangement was obtained, which helps to reduce non-radiative recombination. Ultimately, when the PHT temperature reaches 200 degrees C, we get an optimal device with an efficiency of up to 9.44 %, as open circuit voltage (VOC) escalates to 431 mV, and lower fill factor (FF) attains 55.63 %. It is believed that this PHT process can be better applied in thin film cells to obtain high-efficiency solar cells.

Achieving high open-circuit voltage (VOC) continues to pose a significant challenge for kesterite Cu2ZnSn(S,Se)4 (CZTSSe) solar cells, predominantly due to the pronounced charge carrier recombination occurring at heterointerface (HEI). To address this issue, an innovative non-metallic boron (B)-modification strategy is developed to optimize the HEI. The key advantages of this strategy are as follows: (i) Leveraging the strong bonding characteristic of B with three valence electrons, the dangling bonds on the absorber surface can be fully saturated, effectively passivating surface states without introducing new defects; (ii) Moreover, diffusion of B into the near-surface region of HEI during selenization process can create weak n-type BCu donor defects, which lowers the valence band maximum (VBM) of the absorber and mitigates Fermi level pinning. Thus, a larger degree of downward band bending on the absorber surface is realized, contributing to the efficient charge carrier transport. By fine-tuning the B-modification process, a competitive and stabilized power conversion efficiency (PCE) of 13.35% have been attained, alongside an extraordinary VOC of 0.58 V, which highlights the great potential of modifying the HEI with non-metallic elements for future research.

This study systematically investigates the optimization mechanism of NaClO solution treatment on Mo substrates for enhancing the optoelectronic performance of CZTSSe thin film solar cells. Experimental results demonstrate that a 10 s NaClO soaking forms a "spike-like" texture on the Mo surface, increasing the average surface roughness difference from 34.52 to 77.75 nm. This significantly enhances light scattering, particularly for photons reaching the back Mo electrode, thereby extending the optical path and promoting photon reabsorption. Additionally, the roughened Mo surface improves the wettability of the precursor solution (contact angle decreases from 19.3 degrees to 12.7 degrees), facilitating the formation of larger CZTSSe grains. Electrical characterization reveals that the NaClO-treated Mo substrate significantly reduces the density of negative charge traps at CZTSSe grain boundaries (contact potential difference increases from -1.1 V to -263 mV), suppressing hole recombination and optimizing carrier collection efficiency. The spike-like structure of the Mo surface also shortens the transport path of hole carriers generated by short-wavelength light, further enhancing collection efficiency. Ultimately, the PCE of CZTSSe devices based on the Mo-10 substrate increases from 9.34% to 11.07%, attributed to the reduction in Rs and J0. This study highlights the critical role of a back electrode interface microstructure design in synergistically optimizing light absorption and carrier transport.