How UCLA researchers cleared the nanoscale bottleneck holding back next-gen electronics

FINDINGS

Researchers at UCLA have discovered a way to dramatically improve how electrical current enters perovskite semiconductors, an emerging class of materials with enormous potential for next-generation electronics.

A longstanding challenge has been the metal-perovskite interface, where electrical current often struggles to pass efficiently from the metal electrode into the semiconductor. This interface behaves like a clogged doorway, wasting energy and slowing device performance.

The research team developed a strategy that makes this transition much easier. By creating a very thin, locally modified region under the metal contact, they enabled electrons to pass through the barrier using a quantum mechanical process called tunneling.

This approach reduces the resistance at the contact by shrinking the "blocked" region from about 250 nanometers to less than 25 nanometers. As a result, current can flow more efficiently at lower voltages.

The discovery could enable faster, lower-power and more reliable perovskite electronic devices, marking an important step toward translating these materials from laboratory research into practical technologies.

BACKGROUND

Perovskites are a promising class of materials for solar cells, sensors, photodetectors and advanced electronics because they are highly efficient and inexpensive to manufacture.

However, a major obstacle has limited their adoption in electronic devices: poor electrical contact between metal electrodes and the perovskite semiconductor.

In most traditional semiconductors, engineers solve this problem using impurity doping, which introduces additional charge carriers to improve conductivity. But this strategy is difficult to implement effectively in perovskites because the materials are relatively soft and chemically sensitive.

This research addresses that bottleneck by rethinking how electrical contacts are engineered.

METHOD

Instead of modifying the entire material, the researchers focused on engineering the tiny region directly beneath the metal electrode.

They developed a contact-induced charge-transfer doping method using silver oxide nanoclusters formed at the interface.

The process involved three key steps:

1. A van der Waals-laminated metal electrode was placed on the perovskite surface to minimize damage.
2. Mild thermal annealing allowed small amounts of silver to diffuse into the near-surface region.
3. Ultraviolet light exposure converted the silver into silver oxide nanoclusters.

These nanoclusters act as electron acceptors, pulling electrons away from the perovskite and creating a locally p-doped region beneath the metal contact.

This localized doping dramatically narrows the energy barrier at the interface, enabling charge carriers to pass through via Fowler-Nordheim quantum tunneling rather than traditional thermionic emission.

IMPACT

This work addresses a critical bottleneck in perovskite electronics and offers a new design strategy to improve device performance.

Potential impacts include:

• More efficient perovskite electronic devices
• Lower power consumption
• Improved reliability and stability
• New pathways for developing perovskite-based transistors, photodetectors and optoelectronic devices

While the work is currently at the laboratory proof-of-concept stage, the results demonstrate a promising route for turning perovskites from research materials into practical electronic technologies.

The concept of contact-induced self-doping may also inspire new approaches to engineering interfaces in other emerging semiconductor materials.

AUTHORS

The study's corresponding author is CNSI member Xiangfeng Duan, holder of the Raymond A. and Dorothy A. Wilson Endowed Chair and a distinguished professor of chemistry and biochemistry at the UCLA College. The first authors are Boxuan Zhou, a UCLA doctoral student and Laiyuan Wan, a UCLA postdoctoral fellow.

Other UCLA-based co-authors are Qi Qian, Bangyao Hu, Peiqi Wang, Ao Zhang, Zhong Wan, Kijoon Bang, Shuanghao Zheng, Aamir Hassan Shah, Yiliu Wang, Yihong Ye, Dehui Zhang; and CNSI member Yu Huang, holder of the Traugott and Dorothea Frederking Endowed Chair and a professor of materials science and engineering at the UCLA Samueli School of Engineering.

JOURNAL

Nature Materials

FUNDING

The study was supported by the National Science Foundation.