Factors influencing halide vacancy transport in perovskite solar cells

Abstract

Ion migration in inorganic and hybrid organic-inorganic metal halide perovskites causes unusual phenomena in photovoltaic devices, such as current-voltage hysteresis and photoinduced phase transformations. It is now well established that metal halide perovskites are mixed ionic-electronic conductors and halide ions are mobile at room temperature. The effect of various physical stimuli like light, heat, pressure, and applied bias can affect the distribution and movement of ions. However, the impact of each stimulus is not understood as the measured response includes a combination of factors. We explore, using first-principles density functional theory (DFT), halide migration mediated by vacancies in model cubic phases of CsPbX3 (X = Cl, Br, I) and systematically control the electronic, chemical, and mechanical conditions. We assess the potential energy landscape for ion migration and how device-relevant conditions and compositional engineering can influence the physical behaviour of halide perovskites.

Stable and efficient soft perovskite crystalline film based solar cells prepared with a facile encapsulation method

“…3(d). The migration of iodine ions is possible due to the thermal-driven effect 34 and/ or pressure-driven effect 35 during the encapsulation process. In the encapsulated perovskite solar cell, the V OC hysteresis (ΔV OC ) increases from 18 mV to 34 mV after 9 days (see Fig.…”

Lattice disorder influences the photocarrier dynamics in lead halide perovskites

“…5–7 The lattice structure (phase) 1,8 of LHPs is determined by the distortion and orientation ordering of PbX 6 octahedrons and A-site cations (Table 1). 9–17 To further improve the efficiency, it is extremely important to reveal the relationship between the structure and the underlying physical mechanisms, such as carrier dynamics in the perovskite absorber layer. Although the important influence of both the PbX 6 octahedron and A-site cation has been predicted theoretically, 9–16 their contribution to carrier recombination and diffusion is still unclear limited by the lack of direct experimental evidence.…”

Intrinsic stability of perovskite materials and their operational stability in light-emitting diodes

“…MHPs possess high equilibrium defect densities of 10 16 –10 18 cm −3 due to their low formation energies. 46 Diffusion of these defects facilitates the migration of ions; therefore, OIHPs show mixed ionic–electronic conductivities. Eames et al 47 studied the transport mechanism of ions and vacancy defects in CH 3 NH 3 PbI 3 .…”