Improved Performance of Planar Perovskite Solar Cells Using an Amino-Terminated Multifunctional Fullerene Derivative as the Passivation Layer

Abstract

Organic–inorganic metal-halide perovskite solar cells (PSCs) have been revolutionizing the photovoltaic (PV) community in the past decade. However, the trap states in TiO2 as the electron-transport layer seriously affect the device PV performance and stability. Here, we design and synthesize a fullerene derivative C60NH2 featuring an amino-terminated group. We use C60NH2 as a passivation layer between TiO2 and perovskite in planar PSCs with a standard configuration to improve the quality of the obtained perovskite film as well as the electron-transfer efficiency, resulting in an obvious increment of PV performance and stability of the devices. The champion power conversion efficiency of 18.34% is achieved under 100 mW cm–2 illumination utilizing C60NH2 as the passivation layer with much less hysteresis. Planar PSCs demonstrate superior stability under natural sunlight and 40–50% relative humidity after C60NH2 passivation. This work enriches the choices of materials for interface engineering toward fabrication of planar PSCs with high performance.

Interfaces and Interfacial Layers in Inorganic Perovskite Solar Cells

“…[17] Such ap assivation effect can also be achieved by introducing athin inter-ormonolayer. [18] Furthermore,t hin (few nm) insulating interlayers can be employed that allow tunneling of majority charges but retard surface recombination. [19]…”

“…Among them, organic ammonium salts and nitrogen-functionalized compounds are especially popular. [18,68] Then itrogen functional groups are strong Lewis bases,which can interact with Lewis acidic halide vacancies,t he major defects in metal halide perovskites.I na ddition, such aL ewis base can also interact with Ti vacancies that exist in the undercoordinated TiO 2 lattice. [18] Forexample,byadopting 6TIC-4F with -CN as af unctional group in the CsPbI 2 Br-based PSC,t he chargerecombination lifetime within the device is significantly improved by 1.5 times.T he external quantum efficiency (EQE) of electroluminescence (EL) is also increased by almost one order of magnitude (Figure 7).…”

“…[18,68] Then itrogen functional groups are strong Lewis bases,which can interact with Lewis acidic halide vacancies,t he major defects in metal halide perovskites.I na ddition, such aL ewis base can also interact with Ti vacancies that exist in the undercoordinated TiO 2 lattice. [18] Forexample,byadopting 6TIC-4F with -CN as af unctional group in the CsPbI 2 Br-based PSC,t he chargerecombination lifetime within the device is significantly improved by 1.5 times.T he external quantum efficiency (EQE) of electroluminescence (EL) is also increased by almost one order of magnitude (Figure 7). [69] Likewise, ammonium halides can also passivate the defects at the bottom contact between CTL and perovskite layer, also known as the buried interface,byvarying the morphology and crystallographic structure.…”

Gold Nanoparticles Functionalized with Fullerene Derivative as an Effective Interface Layer for Improving the Efficiency and Stability of Planar Perovskite Solar Cells

“…[ 29–35 ] In particular, fullerenes and their derivatives appeared as excellent interfacial modification layers and trap state passivators for the TiO 2 ETL, significantly enhancing the performance and stability of PSCs. [ 36–38 ] Recent studies revealed that coating the TiO 2 with a thin layer of pristine C 60 , [ 39–42 ] phenyl‐C 61 ‐butyric acid methyl ester (PCBM) [ 43–45 ] or self‐assembled monolayer (SAM) of fullerene derivatives [ 46–48 ] promotes the electron transfer and reduces the ion accumulation at the ETL/perovskite interface. Moreover, an appropriated functionalization of the fullerene derivatives with various anchoring groups can improve the crystallization of the perovskite film on the ETL and substantially eliminate the hysteresis effect of PSCs.…”

Optical degradation impact on the spectral performance of photovoltaic technology

“…1. Most of the studies performed in the area of photovoltaic solar energy have focused on aspects such as improving the efficiency of PV modules [6][7][8][9][10][11][12][13][14][15], reducing costs [16][17][18], optimizing the design of the balance of system (BOS) [19], and the selection of the optimal orientation and inclination of the modules [20][21][22][23][24] . However, in the last 10 years, the number of publications on the different mechanisms of optical degradation, which affect the behaviour of PV modules [25][26][27], have significantly increased, as it is shown in Fig.…”