Hole-Transporting Vanadium-Containing Oxide (V2O5-x) Interlayers Enhance Stability of α-FAPbI3-Based Perovskite Solar Cells (∼23%)

The impact of CBz-PAI interlayer in various HTL-based flexible perovskite solar cells: A drift-diffusion numerical study

In perovskite solar cells (PSCs), the charge carrier recombination obstacles mainly occur at the ETL/perovskite and HTL/perovskite interfaces, which play a decisive role in the solar cell performance. Therefore, this study aims to enhance the flexible PSC (FPSC) efficiency by adding the newly designed CBz-PAI-interlayer (simply CBz-PAI-IL) at the perovskite/HTL interface. In addition, substantial work has been carried out on five different HTLs (Se/Te-Cu2O, CuGaO2, V2O5, and CuSCN, including conventional Spiro-OMeTAD as a reference HTL with and without CBz-PAI-IL), using drift-diffusion simulation to find suitable FPSC design to attain the maximum PCE. Interestingly, PET/ITO/AZO/ZnO NWs/FACsPbBrI3/CBz-PAI/Se/Te-Cu2O/Au device architecture demonstrates the highest achievable power conversion efficiency (PCE) of 27.9 %. The findings of this study confirmed that the reference device (without IL) displays a large valence band edge (VBE)/highest occupied molecular orbital (HOMO) energy level misalignment compared to the modified interface device (with CBz-PAI-IL that reduces VBE/HOMO level mismatch) that eases the hole transport, simultaneously, it reduces the charge carrier recombinations at the interface, resulting in diminished Voc losses in the device. Furthermore, the influence of perovskite absorber thickness and defect density, parasitic resistances, and working temperature are systematically examined to govern the superior FPSC efficiency and concurrently understand the device physics.

Recent Developments in Atomic Layer Deposition of Functional Overlayers in Perovskite Solar Cells

Over the last decade, research in organic-inorganic lead halide perovskite solar cells (PSCs) has gathered unprecedented momentum, putting the technology on the brink of full-scale commercialization. A wide range of strategies have been implemented for enhancing the power conversion efficiency of devices and modules, as well as improving stability toward high levels of irradiation, temperature, and humidity. Another key element in the path to commercialization is the scalability of device manufacturing, which requires large-scale deposition of conformal layers without compromising the delicate structure of the perovskite film. In this context, atomic layer deposition (ALD) tools excel in depositing high-quality conformal films with precise control of film composition and thickness over large areas at relatively low processing temperatures. In this commentary, we will briefly outline recent progress in PSC technology enabled by ALD tools, focusing on layers deposited above the absorber layer. These interlayers include charge transport layers, passivation layers, buffer layers, and encapsulation techniques. Additionally, we will discuss some of the challenges and potential avenues for research in PSC technology underpinned by ALD tools.

Semitransparent Perovskite Solar Cells with Ultrathin Protective Buffer Layers

Semitransparent perovskite solar cells (ST-PSCs) are increasingly important in a range of applications, including top cells in tandem devices and see-through photovoltaics. Transparent conductive oxides (TCOs) are commonly used as transparent electrodes, with sputtering being the preferred deposition method. However, this process can damage exposed layers, affecting the electrical performance of the devices. In this study, an indium tin oxide (ITO) deposition process that effectively suppresses sputtering damage was developed using a transition metal oxides (TMOs)-based buffer layer. An ultrathin (<10 nm) layer of evaporated vanadium oxide or molybdenum oxide was found to be effective in protecting against sputtering damage in ST-PSCs for tandem applications, as well as in thin perovskite-based devices for building-integrated photovoltaics. The identification of minimal parasitic absorption, the high work function and the analysis of oxygen vacancies denoted that the TMO layers are suitable for use in ST-PSCs. The highest fill factor (FF) achieved was 76%, and the efficiency (16.4%) was reduced by less than 10% when compared with the efficiency of gold-based PSCs. Moreover, up-scaling to 1 cm2-large area ST-PSCs with the buffer layer was successfully demonstrated with an FF of ∼70% and an efficiency of 15.7%. Comparing the two TMOs, the ST-PSC with an ultrathin V2Ox layer was slightly less efficient than that with MoOx, but its superior transmittance in the near infrared and greater light-soaking stability (a T80 of 600 h for V2Ox compared to a T80 of 12 h for MoOx) make V2Ox a promising buffer layer for preventing ITO sputtering damage in ST-PSCs.