Ricerc@Sapienza

Poly (triaryl amine) (PTAA) is one of the promising hole transport materials (HTM) for perovskite solar cells. Highly efficient PTAA-devices have been demonstrated in both direct (n-i-p) and inverted (p-i-n) architectures. In the inverted structures, the device suffers
from poor coverage of the perovskite film over the hydrophobic PTAA surface. To address this issue, we exploited an easy and efficient
approach utilizing a short-time UV treatment of the PTAA layer prior to the perovskite deposition. The UV-treatment improved the optical

The power conversion efficiency (PCE) of NiO based perovskite solar cells has recently hit a record 22.1%
with a hybrid organic–inorganic perovskite composition and a PCE above 15% in a fully inorganic
configuration was achieved. Moreover, NiO processing is a mature technology, with different industrially
attractive processes demonstrated in the last few years. These considerations, along with the excellent
stabilities reported, clearly point towards NiO as the most efficient inorganic hole selective layer for lead

The operation of halide perovskite optoelectronic devices, including solar
cells and LEDs, is strongly influenced by the mobility of ions comprising the
crystal structure. This peculiarity is particularly true when considering the
long-term stability of devices. A detailed understanding of the ion migrationdriven
degradation pathways is critical to design effective stabilization
strategies. Nonetheless, despite substantial research in this first decade
of perovskite photovoltaics, the long-term effects of ion migration remain

X-ray photoelectron spectroscopy is a powerful tool for the characterization of molecular and hybrid solar cells. This technique allows for atomic-level characterization of their components as well as for the determination of the electronic structure that governs the key conversion processes. In this chapter, we introduce the basic concepts of electronic structure in molecules and semiconducting materials followed by a description of the concepts of photoelectron spectroscopy and how they relate to electronic structure.

In perovskite solar cells (PSCs), the interfaces are a weak link with respect to degradation. Electrochemical reactivity of the perovskite’s halides has been reported for both molecular and polymeric hole selective layers (HSLs), and
here it is shown that also NiO brings about this decomposition mechanism. Employing NiO as an HSL in p–i–n PSCs with power conversion efficiency (PCE) of 16.8%, noncapacitive hysteresis is found in the dark, which is

Nanostructured NiO as hole selective contact for perovskite solar cells is deposited on ITO from the potentiostatic anodic electrodeposition of NiOOH. Along with the large surface extension due to the honeycomb-like morphology, the electrodeposition route imparts different electrochemical features in respect to the classic sol-gel!derived NiO, which are two interesting features for optoelectronic applications.

The nature of the gas phase product released during the thermal decomposition of CH3NH3PbI3 (methylammonium lead iodide) to PbI2 (lead diiodide) under vacuum is discussed on the basis of thermodynamic predictions, recently published experimental results, and new experiments presented here. From the limited data currently available, the nature of the main decomposition path is not clear because, both, the process releasing HI(g) + CH3NH2(g) (1) and that leading to NH3(g) + CH3I(g) (2) were observed under different conditions.