Enhanced Charge Transport in Conventional Polymer Solar Cells with a Perovskite-Type LaNiO₃ Layer

Abstract

In this study, a novel metal oxide, lanthanum nickelate (LNO) with a perovskite structure, was introduced into a polymer solar cell (PSC) device, replacing the PEDOT:PSS hole transport layer (HTL). The results show that the LNO-based PTB7-Th:PC 71 BM solar cell exhibits a higher circuit current density, power conversion efficiency, and stability compared with a device with PEDOT:PSS HTL. To understand the effect of LNO HTL on the performance of devices, the active layer morphology and charge transport characteristics in PSCs were systematically analyzed. The morphology of active layer was affected by the HTL, which further regulated the generation and transport processes of charge carrier in the PSC device. For the LNO HTL, an appropriate thickness (8 nm) and a small surface roughness (S q = 0.7 nm) can coordinate the energy-level structure of device and improve the interface contact between the FTO electrode and PTB7-Th:PC 71 BM active layer, promoting the charge transport performance of device. Therefore, this work provides a new consideration for the preparation of efficient, stable, and low-cost polymer solar cells.

Co‐La‐Based Hole‐Transporting Layers for Binary Organic Solar Cells with 18.82 % Efficiency

“…When H 2 O 2 was added (i.e., the Co‐La 50% HTL), the Co 2p core‐level spectra exhibited not only Co 2+ species but also Co 3+ species, which demonstrates the partial oxidation of the Co 2+ species by H 2 O 2 [13a, 17c] . As with the La 3d core‐level spectra (Figure 2b), four typical peaks, 836.0 eV (3d 5/2 ), 839.4 eV (3d 5/2 , satellite), 852.8 eV (3d 3/2 ), and 856.2 eV 3d 3/2 , satellite), ascribed to La 3+ species are observed in the Co‐La 50% (w/o H 2 O 2 ) and there is no significant difference between the spectra of Co‐La 50% (w/o H 2 O 2 ) and Co‐La 50% HTL, revealing that the addition of H 2 O 2 has little effect on the La 3+ precursor [13a, 17c] . Secondly, to investigate the effect of La on the composition and valence states, XPS deconvolution analysis was conducted on the samples without H 2 O 2 .…”

“…As shown in the Co 2p core‐level spectra (Figure 2a), four typical peaks, 781.6 eV (2p 3/2 ), 786.5 eV (2p 3/2 , satellite), 797.2 eV (2p 1/2 ), and 803.3 eV (2p 1/2 , satellite) present in the Co‐La 50% (w/o H 2 O 2 ), which are assigned to the Co 2+ species [9] . When H 2 O 2 was added (i.e., the Co‐La 50% HTL), the Co 2p core‐level spectra exhibited not only Co 2+ species but also Co 3+ species, which demonstrates the partial oxidation of the Co 2+ species by H 2 O 2 [13a, 17c] . As with the La 3d core‐level spectra (Figure 2b), four typical peaks, 836.0 eV (3d 5/2 ), 839.4 eV (3d 5/2 , satellite), 852.8 eV (3d 3/2 ), and 856.2 eV 3d 3/2 , satellite), ascribed to La 3+ species are observed in the Co‐La 50% (w/o H 2 O 2 ) and there is no significant difference between the spectra of Co‐La 50% (w/o H 2 O 2 ) and Co‐La 50% HTL, revealing that the addition of H 2 O 2 has little effect on the La 3+ precursor [13a, 17c] .…”

“…Here, H 2 O 2 was used as the oxidizing agent to partially transform Co 2+ to Co 3+ . La is an abundant and environmentally friendly rare earth metal with an electron‐rich outer shell structure, which has been widely used to dope semiconductor materials to modify their photoelectric properties [13a, 17] . It was found that H 2 O 2 and La synergistically functioned on improving the photovoltaic performance of the related OSC devices.…”

Charge Photogeneration and Recombination in Fluorine-Substituted Polymer Solar Cells

“…The external quantum efficiency (EQE) test of the device was conducted according to the literature ( Hu et al, 2021a ). Space charge-limited current measurement (SCLC) of PSC devices was performed using previous methods ( Shang et al, 2020 ). All measurements were carried out at room temperature.…”

Photoelectric Conversion and Device Stability of PM6:PY-IT Solar Cells Based on a Water Solution-Processed MoO3 Hole Transport Layer

“…One is environmental factors, such as humidity, oxygen, high-energy light and temperature, etc. − These external factors can be weakened through the encapsulation strategy of devices. On the other hand, the stability of PSCs is also related to their internal structure, such as device configuration (inverted or conventional), morphology of active layers (a thermodynamic metastable state bulk heterojunction structure), and interface layers. − Herein, the interface layer, as an important component in PSCs, plays multiple roles in regulating the internal energy level, absorbing the high-energy light, enhancing the ohmic contact between the active layer and the electrode, and reducing the interfacial charge recombination. − Hence, the interface layer provides essential support for the efficient and stable output performance of PSCs. PEDOT:PSS is a classical hole transport layer (HTL) with high optical transparency and conductivity for PSCs. − However, it has some defects in moisture absorption and acid corrosivity that can corrode the transparent electrode and active layer, resulting in the stability decrease of PSCs. , To solve the deficiency of PEDOT:PSS, many strategies have been developed to enhance the stability of PSCs, such as double-decked interface layers (PEDOT:PSS/V 2 O 5 , PEDOT:PSS/copper iodide, PEDOT:PSS/MoO 3 , etc.…”