Interfaces and Interfacial Layers in Inorganic Perovskite Solar Cells

Abstract

Owing to their superior thermal stability, metal halide inorganic perovskite materials continue to attract interest for photovoltaics applications. The highest reported power conversion efficiency (PCE) for solar cells based on inorganic perovskites is over 20 %. As this PCE corresponds to 73 % of the theoretical limit, there remains more room for further improving the device PCEs than for improving organic–inorganic hybrid perovskite solar cells (PSCs). The main loss is in the photovoltage, which is limited by interfaces in terms of non‐radiative recombination caused by traps and energy‐level mismatch. Furthermore, inefficient charge extraction at interfacial contacts reduces the photocurrent and fill factor. This Minireview summarizes the recent developments in the fundamental understanding of how the interfaces and interfacial layers influence the performance of solar cells based on inorganic perovskite absorbers. An outlook for the development of highly efficient and stable inorganic PSCs from the interface point of view is also given.

Fluorine‐Containing Passivation Layer via Surface Chelation for Inorganic Perovskite Solar Cells

“…Perovskite films fabricated via traditional solution processing methods are prone to generating electronic defects on the surfaces and grain boundaries (GBs), which serve as non‐radiative recombination centers by capturing free charge carriers, leading to an overall reduction of light‐to‐electric efficiency [35–37] . Moreover, the presence of defects can induce ion migration and perovskite degradation towards light and moisture [38, 39] .…”

Molecular design for perovskite solar cells

“…307,308 The energy level arrangement of the perovskite/molecule/ETL and perovskite/molecule/HTL interface is critical for the device performance, because it dictates the energy loss and charge transfer kinetics at the interface. [309][310][311][312][313][314] 4.5 | Molecular engineer ETL/metal, cathode, and carbon interfaces Organic molecules and polymers are applied to modify the ETL/metal and cathode interfaces, since the interfacial contact and the energy level alignment are often associated with the energy losses and degradation. 315 In addition, organic molecules are deposited at the ETL/metal 316,317 and ITO/C 60 318 interfaces to modify the hydrophobicity and water solubility that affect the device performance.…”

“…For the perovskite/HTL interface, examples of organic molecules that have better chances to improve the device performance include those bearing ammonium and alkyl/phenyl groups, 306 provided that these molecules are compatible with the halide perovskite substrate 307,308 . The energy level arrangement of the perovskite/molecule/ETL and perovskite/molecule/HTL interface is critical for the device performance, because it dictates the energy loss and charge transfer kinetics at the interface 309‐314 …”

Guanidinium Thiocyanate Additive Engineering for High-Performance CsPbIBr2 Solar Cells with an Efficiency of 10.90%

“…6,7 In recent years, allinorganic PSCs have become a new research hotspot. 8,9 Among all-inorganic perovskites, the band gap of the cubic phase CsPbI 3 is the narrowest, about 1.73 eV, and the corresponding PSC achieves a high PCE of over 20%. 10 However, the cubic phase will rapidly transform into the undesired orthorhombic phase at room temperature.…”

“…In the past few years, perovskite solar cells (PSCs) have become superstars owing to their superior optoelectronic properties, and the power conversion efficiency (PCE) has been increased from 3.8 to 25.7%. , Nowadays, the 20.8% PCE of all-inorganic perovskites (CsPbX 3 , X = halide) is still behind that of the organic–inorganic perovskite . However, organic cations methylammonium (MA) and formamidinium (FA) of the organic–inorganic perovskites are easily degraded in a high-temperature environment because of thermal instability and inherent volatility. , Compared with the organic–inorganic perovskite, all-inorganic perovskite exhibits better thermal stability due to the use of inorganic Cs cations to replace volatile organic groups. , In recent years, all-inorganic PSCs have become a new research hotspot. , …”