Light management in monolithic all-perovskite tandem solar cells

Abstract

All-perovskite tandem solar cells represent a promising strategy for breaking the Shockley-Queisser limits inherent in single-junction solar cells. Reasonable light management and optical design are necessary for all-perovskite tandem solar cells to improve power conversion efficiency. In this review, the recent progresses in light management for monolithic all-perovskite tandem solar cells are summarized comprehensively. The current-matching conditions, optical challenges, and potential development trajectories for all-perovskite tandem solar cells are investigated. It includes key optical losses, enhancements and strategies for light trapping and light utilization. Ultimately, forward-looking perspectives on future developments are presented. This review aims to offer valuable insights and practical suggestions for improving power conversion efficiency of all-perovskite tandem solar cells from light management techniques.

Fig. 1. The schematic diagram of light management and APTSCs.

a PSCs without light management, resulting photons either not entering the absorber layer nor escaping from the absorber layer. b Reducing optical losses to maximize photon flux reaching the absorber. c Improving light utilization to ensure photon captured by the absorber and efficiently converted into charge carriers. d 4 T tandem configurations. e 2 T tandem configurations

Fig. 2. Bandgaps design for the APTSCs.

a The schematic diagram of APTSCs constructed by two MAPbI₃ perovskite layers. b The schematic diagram of APTSCs constructed by MAPbBr₃ and MAPbI₃ perovskite. c Theoretical maximum PCEs as a function of the top and back sub-cell bandgaps for 2 T tandem configurations. The white dotted lines mark the lowest bandgap currently accessible to metal halide perovskite semiconductors. The blue solid symbols show bandgap combinations thus far used in making all-perovskite tandems, including 1.82/1.22 eV, 1.85/1.27 eV, 2.0/1.55 eV and 1.55/1.55 eV. d The bowing effect, which is the schematic energy level diagram of the CH₃NH₃Sn_1−xPb_xI₃ (MASn_1−xPb_xI₃) NBG perovskites. e Scanning electron microscope (SEM) image of APTSCs constructed by Pb-Sn perovskite as the back sub-cell. f EQE response values of sub-cells of Fig. 2e. Panel a is reprinted from ref. with permission from Royal Society Chemistry. Panel b is reprinted from ref. with permission from Wiley. Panel c is reprinted from ref. with permission from Springer Nature. Panel d is reprinted from ref. with permission from American Chemical Society. Panels e and f are reprinted from ref. with permission from American Chemical Society

Fig. 3. Thickness adjustment for the APTSCs.

a Implied photocurrent density as a function of the front and back sub-cell thickness for APTSC with Au-based ICL. The implied current density shown by the dashed line is shown in (b). c EQE response values of APTSCs with different NBG perovskite thicknesses. d Absorption coefficient of FA_0.5MA_0.45Cs_0.05Pb_0.5Sn_0.5I₃ (with a bandgap of 1.22 eV), and corresponded thickness of the films. e Implied photocurrent density as a function of the front and back sub-cell thickness for APTSC with ITO NCs-based ICL. f EQE curves of APTSCs with Au-based and ITO NCs-based ICL. g Detailed balance limit (DBL) for series-connected tandem solar cells limit based on the bandgap combination. h EQE and total reflection (1-R) curves of state-of-the-art APTSCs. i Development of WBG perovskite properties and the limited J_sc of the corresponding APTSCs. The properties of WBG perovskite are defined by the ratio of thickness to bandgap without specific physical meaning, and the limited J_sc depends on a sub-cell with a smaller J_sc, derived from the EQE curves. Panels a, c, and h are reprinted from ref. with permission from Springer Nature. Panel d is reprinted from ref. with permission from Springer Nature. Panels e and f are reprinted from ref. with permission from Wiley. Panel g is reprinted from ref. with permission from Wiley

Fig. 4. The optical loss by the front reflection and the front electrodes.

a Simulated spectral absorptance and reflectance of APTSCs. b SEM image of PDMS nanocone (left) and J-V curves of PSCs with and without PDMS nanocone film (right). c Transmittance curves of FTO glass without and with SiO₂ mesoporous films. d EQE curve of the NBG sub-cell with and without an anti-reflective coating of MgF₂ on the glass substrate facing the light. e Illustration of the extraction behavior of photoexcited electrons from perovskite into the etched FTO. f Transmittance and absorbance spectra of the CE-ITO substrates with different doped-concentration. g Spectral evaluation of the EQE (measured and simulated), reflection losses (measured), and absorption losses (simulated) of the tandem cell architecture with a NIR-optimized PDC-IO:H as a front electrode. Panel a is reprinted from ref. with permission from Elsevier. Panel b is reprinted from ref. with permission from American Chemical Society. Panel c is reprinted from ref. with permission from Wiley. Panel d is reprinted from ref. with permission from Royal Society Chemistry. Panel e is reprinted from ref. with permission from Wiley. Panel f is reprinted from ref. with permission from Wiley. Panel g is reprinted from ref. with permission from American Chemical Society

Fig. 5. The optical loss caused by PEDOT: PSS.

Simulated absorptance of APTSCs using a ITO as TCO and a 50 nm PEDOT: PSS HTL, and b IO: H as TCO and a 20 nm PEDOT: PSS HTL in the NBG sub-cell. c Schematic diagram of formation mechanism of PEG-PEDOT: PSS film. d Device structure and EQE curves of APTSCs with taurine. Panels a and b are reprinted from ref. with permission from Wiley. Panel c is reprinted from ref. with permission from Royal Society Chemistry. Panel d is reprinted from ref. with permission from Wiley

Fig. 6. APTSCs with different ICL.

a Thinning C₆₀/PEIE/AZO/IZO/PEDOT: PSS as the ICL. b Simplified C₆₀/SnO₂/IZO/PEDOT: PSS as the ICL. c ICL with an ALD-SnO₂ and ultra-thin Au recombination layer. d Structure schematic diagram of the APTSCs with ITO NCs-based ICLs. e Transmittance and absorbance spectra of the APTSCs with ITO NCs-based ICLs. f Simplified C₆₀/SnO_1.76 as the ICL. g Transmittance spectra of the ICLs with and without metal. Panel a is reprinted from ref. with permission from Elsevier. Panel b is reprinted from ref. with permission from Springer Nature. Panel c is reprinted from ref. with permission from Springer Nature. Panel e is reprinted from ref. and ref. with permission from Wiley. Panel f is reprinted from ref. with permission from Springer Nature. Panel g is reprinted from ref. with permission from American Chemical Society

Fig. 7. The thickness design for NBG PSCs.

a Absorption coefficient of FA_0.7MA_0.3Pb_0.5Sn_0.5I₃ and required thickness of the NBG perovskite films. b without Cd and c with 0.03 mol% Cd addictive in Pb-Sn perovskite films (FA_0.5MA_0.45Cs_0.05Pb_0.5Sn_0.5I₃) with different thickness. d Transient photocurrent decay (TPC) curves of NBG PSCs with 0.0% and 2.5% Cl. Time-resolved photoluminescence (TRPL) curves of NBG perovskites e without and f with 7% GuaSCN additive. Panels b and c are reprinted from ref. with permission from Springer Nature. Panel d is reprinted from ref. with permission from Springer Nature. Panels e and f are reprinted from ref. with permission from AAAS

Fig. 8. APTSCs with improved NBG perovskite films.

a Illustration of the formation of Sn vacancies in mixed Pb-Sn perovskite due to the presence of Sn⁴⁺ in the precursor solution and the suppression of Sn vacancy formation in TRP perovskite because of the absence of Sn⁴⁺. b Schematic illustration of antioxidation and defect passivation at grain surfaces of mixed Pb-Sn perovskite films enabled by FSA. c The number of absorbed molecules for CF3-PA, PA and PEA at temperatures of 300 and 400 K. d The binding energy (E_b) between passivators and various acceptor-like defects. e J-V curves and schematic illustration of APTSCs with PHJ. f Crystal growth process of Pb-Sn perovskite film without and with AAH additive. g J-V curves of all-perovskite tandem modules with AAH additive. Panel a is reprinted from ref. with permission from Springer Nature. Panel b is reprinted from ref. with permission from Springer Nature. Panels c and d are reprinted from ref. with permission from Springer Nature. Panel e is reprinted from ref. with permission from Springer Nature. Panels f and g are reprinted from ref. with permission from AAAS

Fig. 9. The design for micro-/nano-scale structure of APTSCs.

a Top view of equilibrated molecular representations of control and mixed systems. 2PACz and 3-MPA are shown in pink and blue, respectively; Sn and O atoms, shown in the background, are depicted in yellow and red, respectively. b Illustration of the p-i-n device structure and the reflective indices. c Transmittance of glass with planar and textured PEDOT: PSS HTL processed with different concentrations of PS spheres. d Schematic diagram of SWPC-PEDOT: PSS deposition method. e Top-view SEM image of SnOCl HTL with textured morphology. f EQE response of APTSCs with PEDOT: PSS-based and SnOCl-based ICLs. g Top-view SEM images of CPRA at different HCOOCs concentrations with the Scale bar of 1 µm. h Scheme of the single-junction plasmonic solar cell system employed in the simulations. Panel a is reprinted from ref. with permission from Springer Nature. Panels b and c are reprinted from ref. with permission from Royal Society Chemistry. Panel d is reprinted from ref. with permission from Elsevier. Panels e and f are reprinted from ref. with permission from Wiley. Panel g is reprinted from ref. with permission from Elsevier. Panel h is reprinted from ref. with permission from American Chemical Society

Fig. 10. 3J-APTSCs.

Bandgap calculation for 3J-APTSCs by connecting the bandgap of a 1.22 eV and b 1.25 eV NBG sub-cells. c J-V curve of 3J-APTSCs constructed by Xiao et al. d J-V curve of 3J-APTSCs constructed by Wang et al. e J-V and f EQE curves of 3J-APTSCs constructed by Wang et al. g J-V curve of 3J-APTSCs constructed by Wang et al. h EQE spectra of each sub-cell and total EQE spectrum, and i J-V curves of 3J-APTSCs with optical design. Panels a and b are reprinted from ref. with permission from Royal Society Chemistry. Panel c is reprinted from ref. with permission from American Chemical Society. Panel d is reprinted from ref. with permission from Springer Nature. Panels e and f are reprinted from ref. with permission from Springer Nature. Panels g-i are reprinted from ref. with permission from Springer Nature

Fig. 11. Bifacial APTSCs.

a Reflectance spectra of common ground materials. b PGDs (power-generation density) of a bifacial module under different albedos based on a monofacial one. c Schematic diagram of measurement installation for bifacial illumination using two simulators. d Schematic illustration of bifacial monolithic APTSCs. e Energy yield calculation of monofacial and bifacial tandems with various environment conditions. f SEM image of a bifacial APTSCs with a light-trapping resin particle layer. Panel a is reprinted from ref. with permission from Wiley. Panel b is reprinted from ref. with permission from Springer Nature. Panel c is reprinted from ref. with permission from Elsevier. Panels d and e are reprinted from ref. with permission from Springer Nature. Panel f is reprinted from ref. with permission from AAAS

Fig. 12

Emerging trends and novel approaches of APTSCs

Fig. 13. Outlook for APTSCs.

a Schematically representation of PSCs structure with the UC and DC materials. b Spectral responsivity of a Cs_0.05MA_0.1FA_0.85PbI₃ photovoltaic device and the auto-luminescence spectrum of the TbMel:1%Am sample. c I–V and P–V curves of the radio-photovoltaic nuclear battery. d The reflectance spectra and photographs of PSCs with various ITO electrode thickness. e Schematic diagram of a V-shaped perovskite/silicon tandem PV power station. f Total reflectance spectra of PSCs with different HTLs and ETLs under light incident from the glass side at 45°. g Performance (annual energy conversion efficiency, ECE & annual tandem gain of energy yield against equivalent single-junction) comparison of tandem solar cells optimized under AM 1.5 G and under annual real-world solar spectra. Panels b and c are reprinted from ref. with permission from Springer Nature. Panel d is reprinted from ref. with permission from American Chemical Society. Panels e and f are reprinted from ref. with permission from Royal Society Chemistry. Panel g is reprinted from ref. with permission from Elsevier