Surface Engineering of TiO₂ ETL for Highly Efficient and Hysteresis‐Less Planar Perovskite Solar Cell (21.4%) with Enhanced Open‐Circuit Voltage and Stability

Abstract

Interfacial studies and band alignment engineering on the electron transport layer (ETL) play a key role for fabrication of high‐performance perovskite solar cells (PSCs). Here, an amorphous layer of SnO2 (a‐SnO2) between the TiO2 ETL and the perovskite absorber is inserted and the charge transport properties of the device are studied. The double‐layer structure of TiO2 compact layer (c‐TiO2) and a‐SnO2 ETL leads to modification of interface energetics, resulting in improved charge collection and decreased carrier recombination in PSCs. The optimized device based on a‐SnO2/c‐TiO2 ETL shows a maximum power conversion efficiency (PCE) of 21.4% as compared to 19.33% for c‐TiO2 based device. Moreover, the modified device demonstrates a maximum open‐circuit voltage (Voc) of 1.223 V with 387 mV loss in potential, which is among the highest reported value for PSCs with negligible hysteresis. The stability results show that the device on c‐TiO2/a‐SnO2 retains about 91% of its initial PCE value after 500 h light illumination, which is higher than pure c‐TiO2 (67%) based devices. Interestingly, using a‐SnO2/c‐TiO2 ETL the PCE loss was only 10% of initial value under continuous UV light illumination after 30 h, which is higher than that of c‐TiO2 based device (28% PCE loss).

Gradient Energy Alignment Engineering for Planar Perovskite Solar Cells with Efficiency Over 23%

“…Petrozza and co-workers demonstrated that insufficient charge extraction from the perovskite film to the ETL can be remedied using a TiO 2 /PCBM bilayer ETL, and a PCE of 17.9% was achieved. [21] Numerous other efforts have been undertaken to enhance the performance of PSCs with bilayer ETLs, such as SnO 2 @TiO 2 , [22] SnO 2 /PCBM, [23] An electron-transport layer (ETL) with appropriate energy alignment and enhanced charge transfer is critical for perovskite solar cells (PSCs [24] TiO 2 /In 2 O 3 , [25] MgO/TiO 2 , [17] TiO 2 /ZnO, [26] and ZrO 2 /TiO 2 . [21] Numerous other efforts have been undertaken to enhance the performance of PSCs with bilayer ETLs, such as SnO 2 @TiO 2 , [22] SnO 2 /PCBM, [23] An electron-transport layer (ETL) with appropriate energy alignment and enhanced charge transfer is critical for perovskite solar cells (PSCs [24] TiO 2 /In 2 O 3 , [25] MgO/TiO 2 , [17] TiO 2 /ZnO, [26] and ZrO 2 /TiO 2 .…”

“…[16] Recently, researchers have focused on the use of bilayer ETL, [17] and the bilayer stack structure has been demonstrated to be effective for improving device efficiency. [21] Numerous other efforts have been undertaken to enhance the performance of PSCs with bilayer ETLs, such as SnO 2 @TiO 2 , [22] SnO 2 /PCBM, [23] An electron-transport layer (ETL) with appropriate energy alignment and enhanced charge transfer is critical for perovskite solar cells (PSCs). Petrozza and co-workers demonstrated that insufficient charge extraction from the perovskite film to the ETL can be remedied using a TiO 2 /PCBM bilayer ETL, and a PCE of 17.9% was achieved.…”

Light Management in Organic Photovoltaics Processed in Ambient Conditions Using ZnO Nanowire and Antireflection Layer with Nanocone Array

“…Organic photovoltaic (OPV) devices are promising candidates for clean renewable energy harvesting, which have attracted tremendous attention from many research groups due to their application for efficient flexible solar cells and high PCE over 17% for tandem design . In order to improve efficiency of OPV devices for commercial applications, a number of strategies can be employed, such as material development, interface and morphology optimization, or architectural engineering . Polymer semiconductors suffer from low mobilities and short diffusion lengths as compared to other types of semiconductors, which limits the active layer thickness and the light absorption.…”

Strategically Constructed Bilayer Tin (IV) Oxide as Electron Transport Layer Boosts Performance and Reduces Hysteresis in Perovskite Solar Cells

“…Chen and co‐workers and Xue and co‐workers used ZnO/SnO 2 which suppressed interfacial charge recombination and benefit to charge extraction . Kong and co‐workers and Grätzel and co‐workers reported a TiO 2 /SnO 2 structure that adjusted the band alignment to improve V oc , and device stability . Wang and co‐workers introduced a bilayer SnO 2 by tuning F‐doping level in SnO 2 nanocrystal where they demonstrate gradient F‐doped SnO 2 can effectively decrease the band offset and result in higher V oc in the devices .…”