Surface-type nonvolatile electric memory elements based on organic-on-organic CuPc-H

A novel surface-type nonvolatile electric memory elements based on organic semiconductors CuPc and H2Pc are fabricated by vacuum deposition of the CuPc and H2Pc films on preliminary deposited metallic (Ag and Cu) electrodes. The gap between Ag and Cu electrodes is 30–40 μm. For the current–voltage (I–V) characteristics the memory effect, switching effect, and negative differential resistance regions are observed. The switching mechanism is attributed to the electric-field-induced charge transfer. As a result the device switches from a low to a high-conductivity state and then back to a low conductivity state if the opposite polarity voltage is applied. The ratio of resistance at the high resistance state to that at the low resistance state is equal to 120–150. Under the switching condition, the electric current increases ~ 80–100 times. A comparison between the forward and reverse I–V characteristics shows the presence of rectifying behavior.Project supported by the GIK Institute of Engineering Science and Technology, Pakistan and Physical Technical Institute of Academy of Sciences of Tajikistan.Scopu

Numerical simulation to optimize the efficiency of HTM-free perovskite solar cells by ETM engineering

Perovskite solar cells based on carbon electrodes (c-PSCs) without a hole transport material (HTM) have gained considerable interest owing to their cost-effective and simplified structure. However, their application is constrained by a combination of low efficiency and the prevalence of electron transport materials (ETMs), e.g., TiO2, which undergo extreme temperatures during their manufacturing processes. TiO2 also has poor optoelectronic properties, such as low conductivity and mobility. Additionally, when exposed to UV light, TiO2 susceptibility to photocatalysis reduces the materials long-term stability. In present study, an HTM-free device based on FTO/TiO2/CH3NH3PbI3/carbon structure is employed and studied using a one-dimensional Solar Cell Capacitance Simulator (SCAPS-1D). Initially, the design is studied while employing inorganic ETMs, including CdZnS, WS2, WO3, ZnO, ZnOS, and ZnSe, by substituting TiO2, and the impact of each ETM on device performance is evaluated. After ETM optimization, various parameters that affect device performance, such as ETM and absorber thicknesses, doping concentrations, charge carriers mobility, and defect densities at ETM/perovskite interface, have been studied. Under optimized parameters, the design having ZnSe as ETM yields the best results with a Voc of 1.25 V, Jsc of 24.77 mA/cm2, FF of 86.29 %, and PCE of 26.76 %. The presented results thus add more promise and confidence to the ongoing quest for carbon-based, HTM-free PSCs