Buxin Chen

High-performance perovskite memristor based on methyl ammonium lead halides

Memristors are devices that can store and process information based on their switchable internal resistance. Although these devices offer better performance than the conventional technology, the use of materials such as complex metal oxides usually requires high-temperature annealing processing or vacuum processing such as sputtering, which complicates the fabrication of the devices and hinders their development for practical use. Here we show a high-performance memristor based on organometal trihalides and electrochemical active metals, which achieved an on–off current ratio of 1.9 × 109. The devices can be solution-processed at low temperature and in air, which may be further developed into printable electronics. We explored the influence of different metal electrodes and device structures on memristor performance and the results indicated the great potential of methyl ammonium lead halide perovskite for information storage and computing. Our work provides new application prospects for these materials and may also contribute to the better understanding of other perovskite-based optoelectronic devices.

Fiber-shaped perovskite solar cells with 5.3% efficiency

Nowadays, there is an increasing interest in solid solar cells based on organolead trihalides, which have achieved a certified efficiency of 20.1%. The success in perovskite solar cells extended the knowledge of perovskite materials and inspired their study for special solar architectures. Fiber-shaped solar cells are a type of photovoltaic device fabricated on one-dimensional conductive substrates, which could be potential candidates for wearable/portable electronics. In this study, we integrate the structure of Ti/c-TiO2/meso-TiO2/perovskite/spiro-OMeTAD/Au into the fiber format. The fiber-shaped perovskite solar cells achieved a 5.3% PCE under AM 1.5 illumination and an apparent 8.4% efficiency in the diffuse model. The device design required no transparent conductive oxides and a thin film of gold nanoparticles was employed as a semitransparent top electrode. All the processes for device fabrication were easy to handle and energy-saving. The fiber devices exhibited high reproducibility, which could open new doors towards efficient solid fiber shaped photovoltaic cells.

PbCl2-assisted film formation for high-efficiency heterojunction perovskite solar cells

In this work, PbCl2 is used as an additive to assist organolead trihalide perovskite film formation in a two-step sequential deposition process. PbCl2 inhibits PbI2 crystallization and contributes to the full conversion of PbI2 and enhanced perovskite film morphology control. Cl− incorporation into the perovskite improves charge transport within the film, as confirmed by the resulting prolonged photoluminescence lifetime observed. A reaction temperature of approximately 50 °C between the PbI2/PbCl2 film and CH3NH3I isopropanol solution is essential for synthesizing high-performance perovskite solar cells. Addition of PbCl2 results in a perovskite solar cell energy efficiency of 14% and achieves an average efficiency enhancement of approximately 30% compared with that obtained from the control group.

Organolead trihalide perovskite materials for efficient light emitting diodes

Organolead trihalide perovskite materials have been attracting increasing attention due to their promising role in solid solar cells. Several advantages make them potential candidates for optoelectronics: (1) solution- or/and vapor-processed preparation at low temperature; (2) tunable optical bandgap, wide absorption spectrum but narrow photoluminescence peaks; (3) long carrier life time, large diffusion length and high charge mobility; (4) various nanostructures via tuning capping agents and solvents. In this review, we summarize recent attempts toward efficient LEDs based on organolead trihalide perovskite materials. The strategies of materials science, device design and interface engineering are highlighted. Recent development and future perspectives are summarized for practical perovskite light technologies.

High performance fiber-shaped perovskite solar cells based on lead acetate precursor

Research on perovskite solar cells is currently at a high level of activity and many types of special solar architectures have been derived. The fiber-shaped perovskite solar cell (FPSC) is one very important type of these architectures, as it could be a potential power source of portable/wearable electronics. For the first time, we introduce lead acetate as the lead source to improve the perovskite film morphology on highly curved fiber substrates and then enhance the FPSC performance. A large grain size and uniform perovskite film could be obtained via a simple dip-coating process. The FPSCs achieved a PCE of 7.53% and VOC of 0.96 V under AM 1.5 illumination. This non-halide lead source could promote the development of efficient and large-sized devices with solid fiber solar cells.

Neutral-colored semitransparent solar cells based on pseudohalide (SCN−)-doped perovskite

A novel strategy that uses SCN− is introduced to develop neutral-colored, semitransparent perovskite film of discrete islands. Micro-structured arrays of perovskite precursor “islands” are formed from the (SCN−)-doped precursor solution by the spin-coating method and demonstrates the maximum AVT of 50% with a device efficiency of 2.4%.

Memristive property’s effects on the I–V characteristics of perovskite solar cells

The unfavorable I–V characteristics of perovskite solar cells (PSCs), such as the I–V hysteresis phenomena, have been one major obstacle for their future practical application. However, corresponding analysis based on traditional theories have shown non-negligible flaws and failed for satisfactory explanation. To present a novel mechanism, here we utilize for the first time the memristive property of the perovskite material to analyze the I–V characteristics of PSCs. The obtained joint physical model and the deduced equation may help solving the long-existent mysteries of the I–V characteristics of PSCs. On the basis of our analysis and memristor theory, we also propose an original device optimization strategy for PSCs, which may help further increase their performance to the limit.