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Electrostatic Photoluminescence Tuning in All-Solid-State Perovskite Transistors
Vladimir Bruevich, Dmitry Maslennikov, Beier Hu, Artem A. Bakulin, Vitaly Podzorov
TL;DR
Photoconductivity control in field-effect transistors remains underexplored. This paper demonstrates all-solid-state CsPbBr3 perovskite transistors whose photoluminescence is reversibly modulated by gate voltage, approaching nearly 100% external PL quantum yield.
Problem
Photoconductivity control in field-effect transistors remains underexplored.
Method
The paper demonstrates all-solid-state CsPbBr3 perovskite field-effect transistors and uses gate voltage to reversibly modulate their photoluminescence.
Results
Nearly 100% modulation of photoluminescence and external PL quantum yield approaching 100% are reported.
Takeaways & Limitations
The devices provide electrostatically tunable photoluminescence in all-solid-state perovskite transistors.
Takeaways & Limitations
The model does not consider ionic drifts and associated screening effects, limiting applicability when those effects are dominant.
Abstract
from arXiv · showhide
We demonstrate an all solid state semiconductor device, based on epitaxial single crystalline metal halide perovskites, enabling reversible control of a perovskite photoluminescence with a gate voltage. Fundamentally distinct from electroluminescent diodes, such a photoluminescence field effect transistor uses the gate electric field to electrostatically modulate the interfacial density of mobile charges, thereby affecting the radiative and nonradiative recombination channels of photocarriers. Varying the gate voltage in such transistors efficiently changes the rate of nonradiative interfacial recombination and modulates the photoluminescence intensity by 65 to 98 percent (depending on temperature). At favorable gating, nearly complete elimination of non-radiative losses can be achieved. This functionality, coupled with the strong visible-range absorption and emission, possible due to the high absorption coefficient, as well as controllable thickness and macroscopically homogeneous morphology of epitaxial perovskite films, leads to high external photoluminescence quantum efficiencies realized in large-area, thin-film devices. Such high-efficiency, scalable, electrostatically tunable optoelectronic switches broaden the potential applications of metal-halide perovskites in photonics and optoelectronics.
Introduction
Electrostatic tuning of optoelectronic properties remains underexplored compared with conductivity control, while existing material platforms face emission, absorption, or interface limitations. The work addresses this gap using epitaxial single-crystalline CsPbBr3 photoluminescence transistors.
- Motivation: Reversible electrostatic tuning of photoluminescence and photoconductivity remains underexplored relative to conductivity control in FETs.The introduction identifies external electric fields as an underused way to tune optoelectronic properties.
- Existing platforms: Silicon MOS devices can alter surface recombination through carrier redistribution, but silicon emits light inefficiently because it has an indirect bandgap.The cited silicon bandgap is 1.12 eV in the near-infrared.
- Existing platforms: TMD and other excitonic materials offer direct-bandgap emission, yet exciton-related quenching limits operation to low power densities and monolayers absorb only a few percent of incident light.These constraints limit both usable excitation power and maximum light tunability.
- Material rationale: Metal-halide perovskites combine high photoluminescence yield, non-excitonic room-temperature photoexcited states, charge transport, defect tolerance, and a sharp absorption edge.Their synthetic tunability also supports processable and scalable materials with varied dimensionality.
- Contribution: The study demonstrates reversible gate-voltage control of photoluminescence in all-solid-state epitaxial single-crystalline CsPbBr3 transistors.The device modulates mobile charge density at the semiconductor-dielectric interface, and an analytical model captures the main observed trends.
- Contribution: The resulting three-dimensional, non-excitonic, direct-bandgap photoluminescence transistor is proposed as a tunable optical switch for optoelectronics.The introduction names applications including lasing, displays, telecommunications, and optical integrated conductivity.
Results
The study images operating top-gated CsPbBr3 photoluminescence transistors while varying gate voltage and temperature. Gate steps produce reversible, voltage-dependent photoluminescence changes with fast and slow temporal components, including nearly complete switching at low temperature.
- Temporal kinetics: A -10 V gate step produces a rapid initial photoluminescence rise followed by 2–7 s exponential relaxation.The fitted decay constants are 0.54 s at 0 °C and 1.97 s at -20 °C.
- Temporal kinetics: Cooling increases the photoluminescence decay time, with the reported time constant rising from 0.54 to 1.97 s between 0 and -20 °C.The authors associate the slow component with ionic redistribution in the interfacial perovskite region.
- Mechanism: The fast photoluminescence rise is attributed to electronic interaction between photogenerated carriers and gate-induced holes in the accumulation channel.Its magnitude increases at lower temperatures, consistent with stronger gate effects on radiative recombination as mobility increases.
- Low-temperature behavior: At -95 °C, photoluminescence remains reversibly gate-tunable with plateaus, reduced exponential decay, and some hysteresis during voltage sweeps.The intensity is normalized to the relaxed zero-gate photoluminescence intensity.
- Spectral response: Changing gate voltage affects photoluminescence intensity without changing spectral shape or peak position by more than 0.14 nm.This result indicates intensity modulation without a substantial reported shift in the emission spectrum.
Discussion
The model treats PL gating as electrostatic control of interfacial mobile holes that alters photocarrier recombination, while accounting for carrier transport, trapping, and spatial inhomogeneity. It reproduces the observed gate-dependent PL increase, saturation, and threshold behavior, and identifies finite trapping as necessary for gating.
- Model assumptions: Gate voltage controls the density of mobile holes in the perovskite/dielectric accumulation channel.The channel density is modeled through the gate voltage and gate-channel capacitance.
- Model assumptions: Long diffusion lengths allow photocarriers generated near the illuminated interface to rapidly spread through the film and interact with interfacial gate-induced holes.The assumed hierarchy is L_diff > d_film ≫ α^-1 ≫ d_FE.
- Model limitations: The model excludes ionic drift and associated screening, limiting applicability when those effects are dominant.The stated scope favors reduced temperatures or dense single-crystalline materials with reduced disorder.
- Microscopic mechanism: Increasing interfacial hole density boosts bimolecular electron-hole recombination of bulk photocarriers, increasing PL intensity.The model treats bulk photocarriers as effectively interacting with the interfacial mobile-hole population.
- Model validation: The model captures increasing PL with decreasing V_G, saturation at sufficiently negative V_G, and PL leveling off above V_T.It also incorporates spatial threshold-voltage and mobile-carrier variations through Gaussian surface averaging.
- Microscopic mechanism: Finite trap-limited lifetime is necessary for PL gating, whereas the trap-free limit produces gate-independent PL and saturation at high negative gate voltage.The relative gating effect progressively diminishes as τ increases toward infinity.
Summary
The study demonstrates reversible, purely electrostatic photoluminescence gating in all-solid-state CsPbBr3 perovskite transistors and proposes an analytical model of the effect.
- The devices reversibly modulate photoluminescence with gate voltage, achieving nearly 100% modulation under visible-range continuous-wave photoexcitation.The effect is attributed to gate-induced mobile holes affecting bimolecular recombination and the steady-state photocarrier population and lifetime.
- High-quality epitaxial single-crystalline CsPbBr3 enables both efficient charge transport and high photoluminescence efficiency in these transistors.
- The analytical model captures the main experimental observations and estimates microscopic parameters of photocarrier dynamics.
- Purely electrostatic tuning without drawing current provides an electric knob for reversible semiconductor photoluminescence control.
- The demonstrated functionality potentially supports optical switching, sensing, lasing, optical integrated circuits, and telecommunications.
Methods
The devices use epitaxial CsPbBr3 films grown on mica, macroscopic painted contacts, a parylene-N dielectric, and a semitransparent gold top gate for gated photoluminescence measurements.
- Stoichiometric crystalline CsPbBr3 films were grown on mica by vapor-phase epitaxy in helium at 0.1 bar and 100 sccm.Growth occurred across a temperature range of 540–500 °C.
- The resulting large-area crystalline films were 0.4–1.2 μm thick and absorbed nearly 100% of incident visible light.Their optical density exceeded 2.
- Photoluminescence-transistor fabrication followed the reported epitaxial single-crystal CsPbBr3 FET procedure, with an optically semitransparent modification.
- Films were hand-patterned into macroscopic single-crystalline rectangles, with colloidal graphite painted contacts and a 1–1.3 μm parylene-N gate dielectric.
- A conductive, semitransparent 3–10 nm gold film deposited through a shadow mask defined the top gate electrode.
- Gated photoluminescence measurements were performed in a cryogenic optical vacuum chamber with gate voltages from −50 to 50 V.Measurements used two physically different setups operating over temperatures from −95 °C to 20 °C.