High carrier mobility and remarkable photovoltaic performance of two-dimensional Ruddlesden-Popper organic-inorganic metal halides (PA)2(MA)2M3I10 for perovskite solar cell applications

Two-dimensional Ruddlesden-Popper (2DRP) metal halides have attracted extensive attention in photovoltaic applications due to their high stability, low self-doping levels and long-lived free carriers. Among them, (PA)(2)(MA)(2)Pb3I10 presents itself as a superior candidate, demonstrating greater moisture resistance and improved heat and light stability over many other 2DRP metal halides. This study takes on the opportunity to search for lead-free alternatives by investigating the optoelectronic and carrier transport properties, as well as the photovoltaic performance of such (PA)(2)(MA)(2)M3I10 type metal halides as the photovoltaic absorber, where M = Pb, Cd, Cr, Cu, Ge, Mn, Ni, Sn, Yb, Zn. Our results indicate that the bandgap of (PA)(2)(MA)(2)M3I(10) can be tuned to the optimum photovoltaic application range of 0.9-1.6 eV, along with improved optical and enhanced photo-response capacity, when Sn, Cd, Mn, Ge, and Zn are used to replace Pb. In particular, (PA)(2)(MA)(2)Zn3I10 possesses the largest Stokes shift and Huang-Rhys factor, while showing the best photoluminescence tendency and broadest emission nature. (PA)(2)(MA)(2)Ge3I10 displays the most excellent of carrier transport capacities with high mobilities of 73 cm(2) V-1 s(-1 )and 43 cm(2) V-1 s(-1) for electron and hole carriers, respectively, which are even comparable to that of 3D counterparts. Furthermore, (PA)(2)(MA)(2)Zn3I10 is predicted to have the highest power conversion efficiency of 23.36% based on an empirical energy loss (0.5 eV), which is quite close to the Shockley-Queisser limit, thereby featuring it as a suitable absorber for photovoltaic applications. These findings shed light on new strategies for designing and developing lead-free 2DRP metal halides targeted at future applications in photovoltaic solar cell devices.

Automated summary

Two-dimensional Ruddlesden-Popper (2DRP) metal halides, particularly (PA)(2)(MA)(2)Pb3I10, have shown high stability, low self-doping levels, and long-lived free carriers for photovoltaic applications. This study explores lead-free alternatives by investigating the optoelectronic properties and carrier transport capabilities of (PA)(2)(MA)(2)M3I10 metal halides, leading to the discovery that (PA)(2)(MA)(2)Zn3I10 and (PA)(2)(MA)(2)Ge3I10 show promising potential as efficient absorbers in photovoltaic solar cell devices.