CsPbI₃ and DMA-Incorporated CsPbI₃: How Stable Are They?

Area of Science:

• Materials Science
• Photovoltaics
• Solid-State Chemistry

Background:

• Inorganic cesium lead triiodide (CsPbI3) is a promising perovskite solar cell material.
• While CsPbI3 offers better thermal stability than organic-inorganic variants, its device-level thermal stability remains under-investigated.
• Dimethylammonium iodide (DMAI) incorporation reportedly enhances CsPbI3 phase stability, but its thermal stability effects are unclear.

Purpose of the Study:

• To evaluate the high-temperature phase stability of DMAI-doped CsPbI3 films and devices.
• To understand the role of DMAI in the thermal degradation pathways of CsPbI3 perovskites.
• To assess the impact of encapsulation on the thermal stability of DMAI-modified CsPbI3 solar cells.

Main Methods:

• High-temperature phase stability analysis of CsPbI3 films with and without DMAI.
• Investigation of DMAI cation loss and iodide vacancy dynamics at elevated temperatures.
• Comparative study of encapsulated and unencapsulated CsPbI3 solar cells under thermal stress.
• Assessment of photodegradation effects in conjunction with thermal stress.

Main Results:

• DMAI-doped CsPbI3 films exhibit a slower, but similar, phase conversion to non-perovskite phases compared to undoped films, linked to DMA+ cation loss.
• Encapsulation effectively retards DMA+ release and subsequent phase conversion in DMAI-doped CsPbI3 films.
• Despite encapsulation, the DMA+ cation induces photodegradation, exacerbating high-temperature phase instability.

Conclusions:

• High-temperature phase instability is a critical factor for CsPbI3-based solar cell thermal stability.
• DMAI improves phase stability but introduces photodegradation pathways that worsen thermal instability.
• Further research is needed on alternative additives or DMAI replacement for robust CsPbI3 solar cell performance.