2D Ruddlesden-Popper X-FPEAPbI perovskites for highly stable PeLED with improved opto-electro-mechanical properties.

We investigate the opto-electro-mechanical characteristics and stability of Ruddlesden-Popper X-FPEAPbI perovskites, where X represents para (p), meso (m), and ortho (o) configurations. The findings reveal that the transition from para to meso and ortho configurations results in a progressive increase in the bandgap, with values of 2.097 eV, 2.133 eV, and 2.177 eV, respectively. Notably, p-FPEAPbI exhibits superior stability, characterized by an enhanced formation energy of - 4.825 eV, compared to m-FPEAPbI (- 4.647 eV) and o-FPEAPbI (- 4.581 eV). Thus, p-FPEAPbI emerges as a leading candidate for the active layer in perovskite light-emitting diodes (PeLEDs). Internal quantum efficiencies of 6.289% for PEAPbI and 2.285% for p-FPEAPbI have been achieved, both of which are higher than those of MAPbI. In contrast, the dependence of efficiency on temperature fluctuations for p-FPEAPbI is 0.01 1/K, compared to PEAPbI's 0.0282 1/K, highlighting its enhanced stability under temperature changes. Furthermore, the stability of the emission spectrum against temperature fluctuations for p-FPEAPbI, with a value of 0.0156 nm/K, is greater than that of PEAPbI, which has a value of 0.0245 nm/K. Although the efficiency of PeLEDs utilizing p-FPEAPbI is somewhat lower than that of PEAPbI, its superior stability makes it a compelling choice for future applications, paving the way for more reliable and durable light-emitting devices.