Materials Design of Solar Cell Absorbers Beyond Perovskites and Conventional Semiconductors via Combining Tetrahedral and Octahedral Coordination

Abstract

Tetrahedral coordination structures, e.g. crystalline Si, GaAs, CdTe, and octahedral coordination structures, e.g. perovskites, represent two classes of successful crystal structures hitherto for solar cell absorbers. Here, via first‐principles calculations and crystal symmetry analysis, the two classes of semiconductors are shown exhibiting complementary properties in terms of bond covalency/ionicity, optical property, defect tolerance, and stability, which are correlated with their respective coordination number. Therefore, a spinel structure is proposed, which combines tetrahedral and octahedral coordination into a single crystal structure, as an alternative to perovskite and conventional semiconductors for potential photovoltaic applications. The case studies of a class of 105 spinel AB2X4 systems identify five spinel compounds HgAl2Se4, HgIn2S4, CdIn2Se4, HgSc2S4, and HgY2S4 as promising solar cell absorbers. In particular, HgAl2Se4 has suitable bandgap (1.36 eV by GW0 calculation), small direct–indirect bandgap difference (24 meV), appropriate carrier effective mass (me = 0.08 m0, and mh = 0.69 m0), strong optical absorption, and high dynamic stability. This study suggests that crystal systems with mixed tetrahedral and octahedral coordination may open a viable route for emerging solar cell absorbers.

Band-Edge Orbital Engineering of Perovskite Semiconductors for Optoelectronic Applications

“…Metal halide perovskites with a general formula AMX3 (A = Cs, CH3NH3, CH(NH2)2; M = Pb, Sn; X = I, Br, Cl) have received intensive attention due to their excellent electronic and optical properties for perovskite-based optoelectronic applications. [1][2][3] Previous theoretical studies [4][5][6] have revealed that high-symmetry perovskite structure plays a critical role in establishing superior optoelectronic properties. Therefore, in the past few years, exploring the structure-property relationships has become an important guidance for experimental efforts in seeking highperformance halide perovskites.…”

From Pb to Bi: A Promising Family of Pb‐Free Optoelectronic Materials and Devices

“…The reason for its efficiency improvement is mainly due to the superior optoelectronic properties of hybrid perovskite materials, such as direct band gap, large absorption coefficient, suitable and adjustable bandgap, long carrier diffusion length, and high defect tolerance. [11][12][13][14] In particular, high-performance devices can be fabricated by solution processed films due to their high defect tolerance, which is significant for commercialization. Based on these excellent properties, perovskite materials have also been used in other optoelectronic devices, including light-emitting diodes (LEDs), [15][16][17] photodetectors, lasers, etc.…”

Inorganic Halide Perovskite Solar Cells: Progress and Challenges

“…[9] In addition to CsBX 3 , many other types of all-inorganic halide perovskites have been theoretically predicted and synthesized. [10][11][12] All-inorganic perovskite semiconductors have recently drawn increasing attention owing to their outstanding thermal stability. Although all-inorganic perovskite solar cells (PSCs) have achieved significant progress in recent years, they still fall behind their prototype organic-inorganic counterparts owing to severe energy losses.…”