Photodecomposition and Morphology Evolution of Organometal Halide Perovskite Solar Cells

Abstract

We study the photoinduced degradation of hybrid organometal perovskite photovoltaics under illumination and ambient atmosphere using UV-vis absorption, atomic force microscopy, and device performance. We correlate the structural changes in the surface of the perovskite film with changes in the optical and electronic properties of the devices. The photodecomposition of the methylammonium lead triiodide perovskite layer itself proceeds much more slowly than the photodegradation of the performance of devices with fullerene/bathocuproine/aluminum top contacts, indicating that the active layer is more stable than the interface with the electrodes in this geometry. The evolution of the perovskite active layer performance proceeded through several phases: (1) an initial improvement in device characteristics, (2) a plateau with very slow degradation and finally (3) a catastrophic decline in material performance accompanied by marked changes in film morphology. The rapid increase in surface roughness of the active perovskite semiconductor associated with sudden failure also correlates with decreased absorption at the perovskite band edge and growth of a lead iodide absorption feature. We find that degradation requires both light and moisture, is accelerated at increased humidity, and scales linearly with light intensity, depending primarily on total photon dose.

Role of Microstructure in Oxygen Induced Photodegradation of Methylammonium Lead Triiodide Perovskite Films

“…More importantly, crosssection images (Figure 1d-e) show that for PbAc 2 the grains protrude throughout the entire film allowing charges to be transported to the extraction layers within a single grain. [42,45,46] For the PbAc 2 recipe, the inherent water in the precursor solution as well as the addition of hypophosphorous acid results in an enlargement of the grain size and improved film morphology resulting in perovskite films with high electronic quality and low defect density. The difference in microstructure is also accompanied by a significant reduction of the photoluminescence (PL) intensity of the sol-eng layer compared to that of PbAc 2 corresponding to PL quantum efficiency values of ≈10% and ≈0.1% for PbAc 2 and sol-eng, respectively ( Figure S4, Supporting Information).…”

CuP2/C Composite Negative Electrodes for Sodium Secondary Batteries Operating at Room‐to‐Intermediate Temperatures Utilizing Ionic Liquid Electrolyte

“…[17] Ionic liquids (ILs) composed of only cations and anions have low flammability, low volatility, and high thermal stability, [18][19][20] which allow for improved safety characteristics of energy storage devices, and have been investigated as possible electrolytes for Na secondary batteries. [21][22][23] Several groups have shown better performance with ILs compared to organic electrolytes in terms of cycle performance and rate capability. Less resistance in symmetric cell of both negative and positive electrodes in the case of IL compared to organic electrolytes at 298 K was reported in a previous work.…”

Revealing the Self‐Degradation Mechanisms in Methylammonium Lead Iodide Perovskites in Dark and Vacuum

“…Though some significant studies have been invested to discuss the toxicity and stability issues of CH 3 NH 3 PbI 3 PSCs against moisture, heat, and light‐induced trap states, however, the degradation of CH 3 NH 3 PbI 3 PSCs stored in the dark and vacuum has rarely been reported to the best of our knowledge . The major degradation pathways reported so far based on the moisture‐induced structural transformation of CH 3 NH 3 PbI 3 perovskite into wide bandgap hydrate compounds (CH 3 NH 3 PbI 3 ⋅ H 2 O) and (CH 3 NH 3 ) 4 PbI 6 ⋅ 2H 2 O) ,.…”