Huake Li Xin & Yang Junyou team Materials Today Electronics: Research progress on perovskite/Cu(In,Ga)Se2 stacked cells

• Tandem solar cells are expected to revolutionize photovoltaic technology because they have significantly higher power conversion efficiencies compared to the currently dominant single-junction solar cells. The combination of perovskite and CIGS materials in tandem cells has attracted widespread attention due to the excellent light absorption properties of perovskite materials , the solution-based preparation process, and the excellent charge carrier transport characteristics of CIGS. Stability makes its stacked devices uniquely competitive in production applications.

  
  

  
  

  Based on this, the Huake Li Xin & Yang Junyou team made a comprehensive summary of the latest research progress in perovskite/CIGS tandem solar cells, paying special attention to the complex design of the device structure and cutting-edge preparation methods. The key role of interface engineering, material composition optimization and precise control of processing parameters in improving device photovoltaic performance is highlighted. This review demonstrates substantial improvements in efficient photovoltaic conversion and carrier transport by optimizing stacking architectures and material layer interfaces, resulting in improved performance and long-term device stability. Finally, the future development of perovskite/CIGS tandem solar cells is prospected, aiming to promote the further development and practical application of this technology.

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• Fig. 1.Comparative summary of PCE through the research articles over the year.
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• Fig. 2. (a) The two common 2-T and 4-T framework structures in perovskite/CIGS tandem devices. (b) Equivalent circuits of 2-T and 4-T perovskite/CIGS tandem devices under illumination. Rs and Rsh are the series and parallel resistances respectively, I and V are the output current and voltage respectively.

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• Fig. 3. (a) High-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) cross-sectional image and EDX elemental map according to the corresponding tandem device. (b) Perovskite sub-cell architecture and molecule structure image investigated. (c) Molecular structures of (2-{3,6-bis[bis(4-methoxyphenyl)amino]-9H-carbazol-9-yl}ethyl)phosphonic acid (V1036), MeO-2PACz, 2PACz and PTAA materials. (d) Stacked image of the perovskite/CIGS monolithic tandem device. (e) Detailed equilibrium limits of monolithic perovskite/CIGS tandem devices based on materials with different bottom and top bandgaps.

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• Fig. 4. (a) The stacking sequence in a 2-T perovskite/CIGS tandem device and the corresponding cross-sectional SEM image. (b) Schematic and cross-sectional SEM image of the BZO layer-based monolithic perovskite/CIGS tandem device. (c) J-V curves of the perovskite/CIGS tandem device and (d) EQE spectra of the corresponding sub-cells. (e) Stability characterization of perovskite/CIGS tandem devices based on aging conditions of 500 h at 30 °C and continuous 1 sun illumination. PL emission spectrum of (f) 10%-Br and (g) 23%-Br under 1 sun equivalent. PL emission spectrum of (h) 10%-Br and (i) 23%-Br at 2 solar equivalents. (j) PL peak shift as a function of time. (k) J−V characteristic characterization of CIGS devices at 100 mW cm−2 and from 25 to 85 °C. Dependence of (l) VOC on light intensity and temperature, (m) JSC on temperature and (n) FF on light intensity and temperature of target CIGS solar cells.

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• Fig. 5. (a) Top-view, cross-sectional SEM, and atomic force microscopy (AFM) images of the multilayer films in each process flow. (b) The corresponding structure diagram is based on the near-infrared (NIR) transparent PSC device. (c) Schematic of the preparation of mixed-cation halide perovskites via partial ion-exchange reactions. (d) Schematic of the energy levels of the MAPbI3-xBrx material and other layers. (e) Structural configuration of the 4-T perovskite/CIGS tandem device. (f) Microscopic cross-sectional SEM image of the perovskite semitransparent cell based on the perovskite material at 1.62 eV. (g) J-V curves of CIGS cells with and without filtration, and inverse J-V curves and (h) steady-state efficiencies of translucent PSCs under different scan directions. (i) Transmission, absorption, and EQE spectra characterization of transparent PSCs, and CIGS cell-independent EQE spectra in the presence of filters. (j) Cross-sectional SEM image and (k) EQE and transmittance data of semitransparent PSC with 2D/3D heterostructure. (l) Schematic of the process of planar PSCs prepared by GABr-IPA and TL method.

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• Fig. 6. (a) Fourier-transform infrared (FTIR) spectra of PEAI and fluoride-PEAI mixture in bending and stretching mode of N-H group. X-ray photoelectron spectroscopy (XPS) curves for Pb 4f 7/2 and 5/2 core level spectra (b), and I 3d 5/2 and 3/2 core level spectra (c) under multifarious treatments. (d) Ultraviolet photoelectron spectroscopy (UPS) spectra of PVK films. (e) The optimized configuration of the PEAI-F integrated surface with I vacancy and Pb-I anti-site defect in the top view. (f) Illustration of defect passivation by PEA+ and SCN-. (g) High-resolution transmission electron microscope (HRTEM) images of a grain boundary of PVK with low and high magnifications. Right-side images present the fast Fourier transform (FFT) analyses of highlighted regions. (h) Schematic of the Cl integration and PDI treatment. (i) J-V curves of devices based on different treatments. (j) J-V curves of the device in different scanning directions based on the optimal Cl + PDI treatment conditions. Statistical boxplot of (k) PCE, (l) VOC, (m) JSC and (n) FF of the corresponding PSCs .

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• Fig. 7. (a) Spectral absorbance of FTO (Pilkington), ITO (Visiontec), IZO (inner), and IO:H (inner) at a given thickness. (b) Figure of merit: The square resistance Rsq of IZO and IO:H is based on the relationship between different O2 contents and the near-infrared absorption rate ANIR (800-1300 nm). (c) Cross section and (d) corresponding SEM image for the as-cut perovskite device. (e) Schematic of the three-case multijunction solar cell with progressive light management. (f) Integration of IO:H (222) XRD peak areas as a function of annealing temperature. The preparation of IO:H thin films is based on different deposition conditions. XRD patterns of the corresponding IO:H films under (g) 150 °C and (h) 230 °C annealing conditions. (i) Integration of (222) XRD peak areas of IO:H films deposited under conditions (0.6 mPa H2 and 1.0 mPa O2) as a function of annealing time. (j,k) Crystallization of different IO:H thin films based on in situ TEM characterization. (l) Schematic illustration of 4-T perovskite/CIGS tandem device performance improved from 23.7% to 29.5% by modification. (m) Bar graph illustrating further modifications of individual layers, such as thickness optimization of individual layers. (n) Simulated EQE spectra of optimized sub-cells for 4-T perovskite/CIGS tandem devices.

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• Fig. 8.Metal flux rates and sequences for (a) a conventional three-step co-evaporation growth profile, (b) a growth profile depositing a fraction of Ga at the beginning and end of the second step, (c) a growth profile with Cu and Ga co-evaporation in the second step. Profile A, B and C are Cross-sectional SEM images of CIGS based on the above three growth curves. (d) Time-of-flight secondary ions Mass spectrometry (ToF-SIMS) characterization to explore GGI in CIGS prepared based on the above growth profiles. (e) Na and (f) Rb secondary ion mass spectrometry (SIMS) profiles of CIGS films based on different growth profiles. (g) Sectional image of narrow-gap CIGS post-processed by RbF. (h) SEM cross-section of the sample with RbF. (i) Alkali profiles by SIMS with and without RbF PDT in the samples. (j) The VOC of devices with low (0.88) and high (0.96) CGI compositions and different concentrations of RbF post-treatment. (k) Apparent doping density obtained from capacitance-voltage measurements for samples with low (0.87) and high (0.96) Cu concentration at high RbF rate. (l) Urbach energy being judged from the EQE spectrum of the same sample. (m) SEM cross-section of IZO as front contact in the device.

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• Fig. 9. (a) Schematic of the flexible 4-T PVK/CIGS tandem minimodule. (b) J-V and (c) EQE curves of the PVK top minimodule (black), and CIGS bottom minimodule (blue) in a 4-T tandem configuration compared to CIGS stand-alone minimodule (red). (d) Plot of reported efficiency versus device area for PVK/CIGS TSCs and minimodules. (e) The UPS results of CyDTA, SnO2, and C-SnO2. (f) The conductivity measurements of CyDTA, SnO2, and C-SnO2 layers. The (g) steady-state PL and (h) TRPL spectra of wide bandgap PVK films based on different substrates. (i) Schematic and photo of a PVK/CIGS tandem device (active area of 1 cm2). (j) Device structure simulated by SCAPS, where DL1, DL2, and DL3 represent defect layers at each interface, respectively. (k) Simulated PCE as a function of defect density for each layer. (l) Simulated current density-voltage (J-V) curves of devices with different defect densities according to DL1, DL2, and DL3. (m) J-V curves for CIGS with different band-gaps. (n) PVK top cell, CIGS bottom cell, and spectral separation system containing a dichroic mirror.
  
  Original link:
  https://doi.org/10.1016/j.mtelec.2023.100086