Simultaneous band gap narrowing and carrier lifetime prolongation of organic-inorganic trihalide perovskites

TL;DR

Applying controllable hydrostatic pressure to organic-inorganic perovskites simultaneously narrows their band gap and prolongs carrier lifetime, significantly enhancing photovoltaic efficiency without chemical modifications.

Contribution

Demonstrated a novel pressure-based method to improve perovskite solar cell properties by simultaneously tuning band gap and carrier lifetime.

Findings

Achieved up to 70-100% increase in carrier lifetime.

Successfully narrowed band gap under mild pressure (~0.3 GPa).

Showed pressure modulation affects photon-electron interactions.

Abstract

The organic-inorganic hybrid lead trihalide perovskites have been emerging as the most attractive photovoltaic material. As regulated by Shockley-Queisser theory, a formidable materials science challenge for the next level improvement requires further band gap narrowing for broader absorption in solar spectrum, while retaining or even synergistically prolonging the carrier lifetime, a critical factor responsible for attaining the near-band gap photovoltage. Herein, by applying controllable hydrostatic pressure we have achieved unprecedented simultaneous enhancement in both band gap narrowing and carrier lifetime prolongation (up to 70~100% increase) under mild pressures at ~0.3 GPa. The pressure-induced modulation on pure hybrid perovskites without introducing any adverse chemical or thermal effect clearly demonstrates the importance of band edges on the photon-electron interaction and maps a pioneering route towards a further boost in their photovoltaic performance.