Abstract
In inverted perovskite solar cells (PSCs), high-quality perovskite film grown on hole-transporting material (HTM) with pinhole-free coverage and a large grain size is crucial for high efficiency. Here, we report on the growth of pinhole-free and large grain CH3NH3PbI3 crystals favored by a hydrophobic small molecular HTM, namely, 4,4′-Bis(4-(di-p-toyl)aminostyryl)biphenyl (TPASBP). The hydrophobic surface induced by TPASBP suppressed the density of the perovskite nuclei and heterogeneous nucleation, thus promoting the perovskite to grow into a dense and homogeneous film with a large grain size. The CH3NH3PbI3 deposited on the TPASBP exhibited better crystallization and a lower trap density than that on the hydrophilic surface of indium tin oxide (ITO), resulting in a significant reduction in carrier recombination. Combined with the efficient hole extraction ability of TPASBP, a high efficiency of 18.72% in the inverted PSCs fabricated on TPASBP was achieved.
Highlights
Between 2009 and 2019, the efficiency of perovskite solar cells (PSCs) was boosted from 3.8%to over 24% [1,2,3,4,5] in individual devices
With the incessant optimization of high efficiency PSCs, the power conversion efficiency (PCE) of inverted PSCs based on PEDOT:PSS has increased from 3.9%, which was reported by Chen et al for the first time in
The as-prepared TPASBP solution was firstly spun onto the indium tin oxide (ITO) with the spin speed of 3000 revolutions per minute for 40 s and annealed at 100 ◦ C for 10 min, which afforded a thickness of ∼20 nm
Summary
Between 2009 and 2019, the efficiency of perovskite solar cells (PSCs) was boosted from 3.8%to over 24% [1,2,3,4,5] in individual devices. In a typical PSC, whether a regular or inverted structure, a several hundred nanometer thick perovskite layer is sandwiched between the electron and the hole transporting layers. For the so-called inverted structure, a multilayer stack of transparent electrode/hole-transporting material (HTM)/perovskite/electron-transporting material (ETM)/metal electrode is fabricated, where the HTM, an important component of PSCs, plays a significant role in hole extraction and transport [6,7], along with affecting the growth of perovskite films [8,9,10]. The HTMs employed in inverted PSCs are mainly p-type wide band-gap semiconductors, which can be divided into conductive polymers and inorganic p-type semiconductors. Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) (PEDOT:PSS) is a widely used HTM due to its favorable conductivity and high transmittance [11,12]. With the incessant optimization of high efficiency PSCs, the power conversion efficiency (PCE) of inverted PSCs based on PEDOT:PSS has increased from 3.9%, which was reported by Chen et al for the first time in
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