Grain Engineering for Improved Charge Carrier Transport in Two-Dimensional Lead-Free Perovskite Field-Effect Transistors

Piperidine and Pyridine Series Lead-Free Dion–Jacobson Phase Tin Perovskite Single Crystals and Their Applications for Field-Effect Transistors

“…Lastly, we successfully demonstrated a p-type FET based on the DJ phase 4AMPSnI 4 perovskite. The device had a simple top-contact bottom-gate (TCBG) architecture and produced respectable hole mobility, μ h of 0.57 cm 2 V –1 s –1 with the lowest threshold voltage of only −2.5 V. Our μ h is comparable to those of the majority RP (0.30–1.45 cm 2 V –1 s –1 ) ,− and DJ (0.58–1.60 cm 2 V –1 s –1 ) , phase Sn-based perovskite FET devices demonstrated to-date (Table S1). Our results clearly demonstrate the promise of DJ phase Sn-layered perovskites and unveil the intricacies of their structures and their relationships to optoelectronic properties important for device demonstrations.…”

“…While such a result is encouraging, reviving the interests in perovskite transistors, such a high μ h value has not been repeated in subsequent reports for layered perovskite FETs. It is worth mentioning that most of the current studies on layered (Pb-containing or Pb-free) perovskite transistors are based on RP-phase layered perovskites, e.g., PEA 2 SnI 4 (Table S1) for Pb-free perovskites. ,− Given the potential advantage of the DJ phase over the RP phase with lower exciton binding energy and higher out-of-plane conductivity as discussed above, there are ample opportunities for discovering new Pb-free DJ perovskite with tailored material properties for FET applications. The majority of the DJ phase perovskites published are lead-based perovskites (around 90 reports to date, there have been only 6 reports of Pb-free Sn-based DJ phase perovskites worldwide. − ,, While many options for DJ perovskites exist, , (aminomethyl)­piperidinium (AMP) and (aminomethyl)­pyridine (AMPY) are promising as they have small piperidine and pyridine structures that provide effective anchoring between the inorganic octahedral layers thereby reducing the separation distance.…”