Molecular Memory with Phase Change Coordination Polymers for future PCRAM – MEMOL

Every day, we create 2.5 quintillion (2.5 E30) bytes of data, so much that 90 % of the data in the world today has been created in the last two years alone. The discovery of a universal memory that exhibits fast access speed, high-density storage, and non-volatility has fueled research into phase-change memory (PCM) over the past decade. Phase-Change Random Access Memory (PCRAM) is currently the most mature of the new memory technologies under research. Chalcogenide, such as Ge2Sb2Te5 and derivate, has been found to be the appropriate candidate. However, the chalcogenide and related inorganic materials have three inherent drawbacks:
1. High temperature is required for phase change which is energy consuming.
2. Domain size of phase change is not small enough.
3. Because of the materials’ brittleness, the fabrication of devices is limited.
To develop new-material-based PCRAM for future all electro-devices, a new class of phase changeable solid is essential. Thus the contribution of molecular technology can help with the appropriated molecules to overcome the limitations of inorganic solids.
We propose “coordination polymer PCM” in this project as an alternative to chalcogenides. Coordination polymers (CPs) are crystalline framework materials that have aligned organic molecules through coordination bonds. The reasons why we consider CPs are a real breakthrough material for future PCRAM, are:
(i) Some CPs show fast and reversible crystal-to-amorphous phase transitions by heat or light exposure. This has just been discovered by some of us in 2015.
(ii) The phase transition behavior (temperature, domain, number of transitions, etc.) can be tuned by organic molecule design. This is beneficial to control the energy consumption.
(iii) The CPs enable to fabricate various devices including flexible (and wearable) devices because these hybrid materials are soft. This is distinct to the conventional inorganic material-based.

So we target to design functional organic molecules to be aligned in CP crystal having versatile manner, and aim to control the reversible phase change for memory application. The ambition of this project stems on the challenge of replacement of all non-volatility memories by this “molecular-based” Phase Change material.
This research uses a complete toolbox of molecular technology, which includes:
1) Design and synthesis of new functional organic molecules which provide new multifunctional Phase Change CPs (PCCPs).
2) Shape and structure controls of the amorphous and crystalline CP phases and their reversibility will be modulated with physical stimuli.
3) Electronic state control of the new amorphous and crystalline CPs relating to their switchable photoluminescence and conductivity is targeted.
4) Aggregates and composite control of the materials will be carried out to get macroscopic objects ready to be evaluated as a memory device.
This project brings together 6 partners in France and Japan. The exchange plan is based on the complementary expertises of the partners and equal partnership. Each partner is able to connect special facilities such as Synchrotron or 900 MHz NMR which is important to proceed this research with high standard and speed. By using the molecular technology and designing organic molecules with the appropriate functionality, we intend to create emerging hybrid PCRAM. In addition, to show the feasibility and miniaturization of PCCP as PCRAM, thin films will be made. Based on the great tunability of these hybrid materials and the large diversity of combinations of organic molecules and metals a new generation of non-volatile memories will be developed and may overcome the limitations of chalcogenide derivatives in term of speed, power, density, data retention, scalability and cyclability.