Self-assembling monolayer-assisted perovskite growth enable
high-performance solar cells
Abstract
Inverted (p-i-n) perovskite solar cells (PSCs) are favored by
researchers owing to their superior compatibility with flexible
substrates and tandem device fabrication. Additionally, the hole
transport layer (HTL) serves as a template for perovskite growth, which
is critical for enhancing the device performance. However, the current
research on how the HTL promotes perovskite crystallization is
insufficient. Here, 4PADCB, a self-assembled monolayer (SAM) hole
transport material, was optimized as a superior template for perovskite
growth through comparative analysis; accordingly, compact perovskite
film with vertical growth was prepared. The better matched energy level
alignment between 4PADCB and perovskite suppressed nonradiative
recombination at the interface and enabled rapid hole extraction.
Moreover, high-quality perovskite film growth on 4PADCB exhibited lower
Young’s modulus and less residual stress. By integrating 4PADCB into
p-i-n PSCs, the optimal device achieved a power conversion efficiency of
24.80%, with an open-circuit voltage of 1.156 V, thus achieving the
best rank among devices without perovskite post-treatment, additives,
dopants, or intermediate layers. Furthermore, the unencapsulated device
demonstrated exceptional thermostability and photostability under
maximum power point tracking. Thus, this work provides a new
understanding for the development of novel SAMs and perovskite growth,
and it is expected to further improve device performance.