High-performance electrolyte-gated conjugated polymer-capped perovskite transistors with conjugated polyelectrolyte as a work function modifier

Conjugated polyelectrolytes (CPEs) are a class of promising semiconducting materials and excellent interfacial work function modifiers for electronic devices. Here, we observed a dramatic improvement of the hole carrier mobility in hybrid methylammonium lead iodide perovskite-conjugated polymer field-effect transistors (FETs) using CPE as an interfacial work function modifier. The fabricated hybrid conjugated polymer-perovskite FETs with ultrathin CPE layers (<5 nm) exhibited an exceptional hole mobility of over 25 cm² V⁻¹ s⁻¹ (average ≈ 20.36 ± 4.31 cm² V⁻¹ s⁻¹) at sub-2 V, thereby significantly exceeding that of the control devices (average hole mobility ≈ 11.70 ± 1.34 cm² V⁻¹ s⁻¹) with the high-capacitance electrolytic gate dielectric. The remarkable performance would be attributed to the improved charge carrier density in the hybrid channel, a larger grain size of perovskite on the CPE layer and a reduced hole injection barrier induced by the organized dipole at an Au/CPE interface. Our findings will provide an insight into the characteristics of CPE-modified contacts for polymer- and perovskite-related electronic devices.