Reassessing the Validity of Space-Charge-Limited Current Measurements in Perovskite Devices with Charge-Transporting...

Area of Science:

• Materials Science
• Solid State Physics
• Device Physics

Background:

• Space-charge-limited current (SCLC) analysis is a common method for determining trap densities and carrier mobility in perovskite materials.
• The applicability of SCLC in multilayer perovskite devices with charge-transporting layers (CTLs) and the role of coupled ionic-electronic transport are not well understood.

Purpose of the Study:

• To critically reassess the validity of SCLC measurements in multilayer perovskite devices.
• To develop a physics-based model that accounts for ionic trap dynamics in halide perovskites.

Main Methods:

• Development of a drift-diffusion model incorporating ionic trap dynamics and charge transition levels.
• Experimental SCLC measurements using a prebias and rapid forward-scan technique.
• Comparison of theoretical simulations with experimental data.

Main Results:

• The SCLC response in multilayer perovskite devices is primarily influenced by CTLs (e.g., Spiro-OMeTAD), not by traps within the perovskite layer.
• The minimum resolvable trap density is limited by the CTL at low perovskite ion densities.
• At high ion densities, space-charge effects are dominated by electric field screening from iodide interstitials.
• Extracted mobility values at high voltages correspond to CTL mobility, not perovskite mobility.

Conclusions:

• Conventional SCLC analysis has fundamental limitations for characterizing multilayer perovskite devices.
• Revised theoretical frameworks are required for accurate characterization of perovskite-based devices, considering ionic and electronic transport.