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Inkjet printing is a more sustainable and scalable fabrication method than spin coating for producing perovskite solar cells (PSCs). Although spin-coated SnO2 has been intensively studied as an effective electron transport layer (ETL) for PSCs, inkjet-printed SnO2 ETLs have not been widely reported. Here, we fabricated inkjet-printed, solution-processed SnOx ETLs for planar PSCs. A champion efficiency of 17.55% was achieved for the cell using a low-temperature processed SnOx ETL. The low-temperature SnOx exhibited an amorphous structure and outperformed high-temperature crystalline SnO2. The improved performance was attributed to enhanced charge extraction and transport and suppressed charge recombination at ETL/perovskite interfaces, which originated from enhanced electrical and optical properties of SnOx, improved perovskite film quality, and well-matched energy level alignment between the SnOx ETL and the perovskite layer. Furthermore, SnOx was doped with Cu. Cu doping increased surface oxygen defects and upshifted energy levels of SnOx, leading to reduced device performance. A tunable hysteresis was observed for PSCs with Cu-doped SnOx ETLs, decreasing at first and turning into inverted hysteresis afterwards with increasing Cu doping level. This tunable hysteresis was related to the interplay between charge/ion accumulation and recombination at ETL/perovskite interfaces in the case of electron extraction barriers.

Perovskite solar cells (PSCs) are emerging as promising candidates for next-generation photovoltaic technologies, primarily due to their high efficiency and cost-effective manufacturing. A critical challenge in maximizing PSC performance lies in achieving consistent and efficient charge extraction and transport. This study investigates the energy alignment and electron transport in a ZnSe-based electron transport layer (ETL), focusing on their optical and electrical properties to enhance the efficiency of lead-free double perovskite solar cells. We utilize the 1D Solar Cell Capacitance Simulator (SCAPS-1D) to evaluate a lead-free double perovskite (Cs2BiAgI6) light absorber, noted for its environmental compatibility. By strategically manipulating key parameters such as doping density and defect concentration, along with optimizing layer thickness, we significantly enhance the power conversion efficiency (PCE) of Cs2BiAgI6-based double PSCs. Particularly, the incorporation of ZnSe as the ETL leads to an optimized PCE of 30.19%. We examine the impact of three different hole transport layers (HTLs) on device performance: MoO3, Cu2O, and spiro-OMeTAD. We also investigate how fluctuations in operating temperature affect the PCE of Cs2BiAgI6 in real time. Our findings highlight the critical role of the ETL in improving charge transport, offering valuable insights for the development and practical application of high-performance double PSCs.

Abstract Sol–gel processed zinc oxide (ZnO) is one of the most widely used electron transport layers (ETLs) in inverted organic solar cells (OSCs). The high annealing temperature (≈200 °C) required for sintering to ensure a high electron mobility however results in severe damage to flexible substrates. Thus, flexible organic solar cells based on sol–gel processed ZnO exhibit significantly lower efficiency than rigid devices. In this paper, an indium‐doping approach is developed to improve the optoelectronic properties of ZnO layers and reduce the required annealing temperature. Inverted OSCs based on In‐doped ZnO (IZO) exhibit a higher efficiency than those based on ZnO for a range of different active layer systems. For the PM6:L8‐BO system, the efficiency increases from 17.0% for the pristine ZnO‐based device to 17.8% for the IZO‐based device. The IZO‐based device with an active layer of PM6:L8‐BO:BTP‐eC9 exhibits an even higher efficiency of up to 18.1%. In addition, a 1.2‐micrometer‐thick inverted ultrathin flexible organic solar cell is fabricated based on the IZO ETL that achieves an efficiency of 17.0% with a power‐per‐weight ratio of 40.4 W g−1, which is one of the highest efficiency for ultrathin (less than 10 micrometers) flexible organic solar cells.

Perovskite solar cells (PSCs) have experienced an unprecedented advancement in the last decade owing to their astonishingly attractive properties, especially high-power conversion efficiency (PCE). In this study, the influence of reduced graphene oxide (rGO) on the photovoltaic performance of perovskite solar cells prepared via solution processes-based spin coating method was investigated. X-ray Diffraction (XRD), Fourier Transform Infrared spectrometer (FTIR), UV-visible spectrophotometry, Scanning Electron Microscopy (SEM) were used to study the properties of the prepared films. ITO/MAPbBr3/Gr and ITO/rGO/MAPbBr3/Gr planar PSCs were fabricated via spin coating method. ITO/rGO/MAPbBr3/Gr film achieved a power conversion efficiency (PCE) of 4.1 short circuit current (Jsc) of 7.5 mAcm−2 and fill factor (FF) of 61.2% compared to a PCE of 3.6%, Jsc of 6.6 mAcm−2 and FF of 58.0% achieved compared to PCE of 3.6%, %, Jsc of 6.6 mAcm−2 and FF of 58.0% achieved by ITO/MAPbBr3/Gr film. The PSC demonstrated the percentage enhancement value of 16.80% when modified with rGO. This study shows that rGO generated functional groups that act as conducting bridge in reducing the contact resistance between interface of the device.

Abstract MXenes, a class of two-dimensional (2D) transition metal carbides and nitrides, have a wide range of potential applications due to their unique electronic, optical, plasmonic, and other properties. SnO2–Ti3C2 MXene with different contents of Ti3C2 (0.5, 1.0, 2.0, 2.5 wt‰), experimentally, has been used as electron transport layers (ETLs) in Perovskite Solar Cells (PSCs). The SCAPS-1D simulation software could simulate a perovskite solar cell comprised of CH3NH3PbI3 absorber and SnO2 (or SnO2–Ti3C2) ETL. The simulation results like Power Conversion Efficiency (PCE), Open circuit voltage (VOC), Short circuit current density (JSC), Fill Factor (FF), and External Quantum Efficiency (EQE) have been compared within samples with different weight percentages of Ti3C2 MXene incorporated in ETL. Reportedly, the ETL of SnO2 with Ti3C2 (1.0 wt‰) effectively increases PCE from 17.32 to 18.32%. We simulate the role of MXene in changing the ideality factor (nid), photocurrent (JPh), built-in potential (Vbi), and recombination resistance (Rrec). The study of interface recombination currents and electric field shows that cells with 1.0 wt‰ of MXene in SnO2 ETL have higher values of ideality factor, built-in potential, and recombination resistance. The correlation between these values and cell performance allows one to conclude the best cell performance for the sample with 1.0 wt‰ of MXene in SnO2 ETL. With an optimization procedure for this cell, an efficiency of 27.81% is reachable.