Influence of Perovskite Interface Morphology on the Photon Management in Perovskite/Silicon Tandem Solar Cells

Tungsten-Doped ZnO as an Electron Transport Layer for Perovskite Solar Cells: Enhancing Efficiency and Stability

This study delves into enhancing the efficiency and stability of perovskite solar cells (PSCs) by optimizing the surface morphologies and optoelectronic properties of the electron transport layer (ETL) using tungsten (W) doping in zinc oxide (ZnO). Through a unique green synthesis process and spin-coating technique, W-doped ZnO films were prepared, exhibiting improved electrical conductivity and reduced interface defects between the ETL and perovskite layers, thus facilitating efficient electron transfer at the interface. High-quality PSCs with superior ETL demonstrated a substantial 30% increase in power conversion efficiency (PCE) compared to those employing pristine ZnO ETL. These solar cells retained over 70% of their initial PCE after 4000 h of moisture exposure, surpassing reference PSCs by 50% PCE over this period. Advanced numerical multiphysics solvers, employing finite-difference time-domain (FDTD) and finite element method (FEM) techniques, were utilized to elucidate the underlying optoelectrical characteristics of the PSCs, with simulated results corroborating experimental findings. The study concludes with a thorough discussion on charge transport and recombination mechanisms, providing insights into the enhanced performance and stability achieved through W-doped ZnO ETL optimization.

Revealing the full potential of CsPbIBr2 perovskite solar cells: advancements towards enhanced performance

Cesium lead iodide bromide (CsPbIBr2) perovskite solar cells (PSCs) have improved stability compared to other perovskite compositions. However, they still face significant challenges due to their poor photovoltaic performance parameters, which limit the devices' power conversion efficiencies (PCEs). This study proposes a novel device design to tailor the potential of CsPbIBr2 PSCs by improving their optoelectronic properties. An advanced 3D multiphysics approach was rigorously used to investigate the optics and electrical properties of the proposed CsPbIBr2 PSCs. This approach combines finite-difference time-domain (FDTD) and finite element method (FEM) techniques with the particle swarm optimization (PSO) algorithm. The outcome from the adapted numerical approach is in good agreement with the experimental results. The optimized CsPbIBr2 PSC demonstrates a promising power conversion efficiency (PCE) of over 16.4%, associated VOC of 1.53 V, FF of 80.6%, and JSC of 13.4 mA cm-2. Therefore, the potential of CsPbIBr2 perovskites could be further explored with continued research and development in material science and device physics.

The Development of Carbon/Silicon Heterojunction Solar Cells through Interface Passivation

Passivating contactsin heterojunction (HJ) solar cells have shown great potential in reducing recombination losses, and thereby achieving high power conversion efficiencies in photovoltaic devices. In this direction, carbon nanomaterials have emerged as a promising option for carbon/silicon (C/Si) HJsolar cells due to their tunable band structure, wide spectral absorption, high carrier mobility, and properties such as multiple exciton generation. However, the current limitations in efficiency and active area have hindered the industrialization of these devices. In this review, they examine the progress made in overcoming these constraints and discuss the prospect of achieving high power conversion efficiency (PCE) C/Si HJ devices. A C/Si HJ solar cell is also designed by introducing an innovative interface passivation strategy to further boost the PCE and accelerate the large area preparationof C/Si devices. The physical principle, device design scheme, and performanceoptimization approaches of this passivated C/Si HJ cells are discussed. Additionally, they outline potential future pathways and directions for C/Si HJ devices, including a reduction in their cost to manufacture and their incorporation intotandem solar cells. As such, this review aims to facilitate a deeperunderstanding of C/Si HJ solar cells and provide guidance for their further development.

Oxidized Nickel to Prepare an Inorganic Hole Transport Layer for High-Efficiency and Stability of CH3NH3PbI3 Perovskite Solar Cells

In this study, we report a perovskite solar cell (PSC) can be benefited from the high quality of inorganic nickel oxide (NiOx) as a hole transport layer (HTL) film fabricated from the physical vapor deposition (PVD) process. The power conversion efficiency (PCE) of PSC is found to depend on the thickness of NiOx HTL. The NiOx thickness is optimized via quantitative investigation of the structure, optical and electrical properties. With an active area of 11.25 cm2, a PSC module (25 cm2) with a PCE of 15.1% is demonstrated, while statistically averaged PCE = 18.30% with an open voltage (Voc) 1.05 V, short-circuit current density (Jsc) 23.89 mA/cm2, and fill factor (FF) 72.87% can be achieved from 36 devices with smaller active areas of 0.16 cm2. After the stability test at 40% relative humidity (RH) and 25 °C for 1200 h, the highest performance NiOx-based PSC is shown to be about 1.2–1.8 times superior to PEDOT:PSS organic HTL based PSC at the same environment.

Tailoring the Energy Band Structure and Interfacial Morphology of the ETL via Controllable Nanocluster Size Achieves High-Performance Planar Perovskite Solar Cells

Planar-type perovskite solar cells (p-PSCs) based on SnO₂ have garnered further attention due to their simple and low-temperature fabrication. Improving the critical properties of the electron transport layer (ETL) is an effective way to enhance the performance of p-PSC devices. Here, a brand-new method is developed to relieve the contact recombination caused by the rough fluorine-doped tin oxide (FTO) surface and further boosts the electrical concentration of the ETL. A SnO₂-ethylene diamine tetraacetic acid (EDTA) acylamide compound (SEAC) with hydrogen bond-induced adjustable cluster size is reported for the first time. The rational choice of the SEAC cluster size is the key for obtaining the smooth interfacial morphology of the ETL on the rugged FTO substrate. In addition, the energy band gap decreases with the increasing cluster size, and consequently, results in improved electrical conductivity of the SEAC. The upshifted Fermi energy level leads to higher electron concentration, which is an important physical quantity of the ETL. The PSC devices based on the optimized SEAC achieve an improved power conversion efficiency of 21.29% with negligible J-V hysteresis due to significantly enhanced electron transport and reduced contact charge recombination at the ETL/perovskite interface. In general, this paper comes up with a unique strategy to improve the quality of the SnO₂-based ETL.

Multimodal Microscale Imaging of Textured Perovskite-Silicon Tandem Solar Cells

Halide perovskite/crystalline silicon (c-Si) tandem solar cells promise power conversion efficiencies beyond the limits of single-junction cells. However, the local light-matter interactions of the perovskite material embedded in this pyramidal multijunction configuration, and the effect on device performance, are not well understood. Here, we characterize the microscale optoelectronic properties of the perovskite semiconductor deposited on different c-Si texturing schemes. We find a strong spatial and spectral dependence of the photoluminescence (PL) on the geometrical surface constructs, which dominates the underlying grain-to-grain PL variation found in halide perovskite films. The PL response is dependent upon the texturing design, with larger pyramids inducing distinct PL spectra for valleys and pyramids, an effect which is mitigated with small pyramids. Further, optimized quasi-Fermi level splittings and PL quantum efficiencies occur when the c-Si large pyramids have had a secondary smoothing etch. Our results suggest that a holistic optimization of the texturing is required to maximize light in- and out-coupling of both absorber layers and there is a fine balance between the optimal geometrical configuration and optoelectronic performance that will guide future device designs.

Atomic layer deposition of metal oxides for efficient perovskite single-junction and perovskite/silicon tandem solar cells

Aluminum-doped and undoped zinc oxide films were investigated as potential front and rear contacts of perovskite single and perovskite/silicon tandem solar cells. The films were prepared by atomic layer deposition (ALD) at low (<200 °C) substrate temperatures. The deposited films were crystalline with a single-phase wurtzite structure and exhibit excellent uniformity and low surface roughness which was confirmed by XRD and SEM measurements. Necessary material characterizations allow for realizing high-quality films with low resistivity and high optical transparency at the standard growth rate. Spectroscopic ellipsometry measurements were carried out to extract the complex refractive index of the deposited films, which were used to study the optics of perovskite single junction and perovskite/silicon tandem solar cells. The optics was investigated by three-dimensional finite-difference time-domain simulations. Guidelines are provided on how to realize perovskite solar cells exhibiting high short-circuit current densities. Furthermore, detailed guidelines are given for realizing perovskite/silicon tandem solar cells with short-circuit current densities exceeding 20 mA cm⁻² and potential energy conversion efficiencies beyond 31%.

The necessity of thin and highly doped metal oxide films is discussed for realizing efficient perovskite single and perovskite/silicon tandem solar cells.