In the present study, random current fluctuations measured at different temperatures and for different illumination levels are used to understand the charge carrier kinetics in methylammonium lead iodide CH₃NH₃PbI₃‐based perovskite solar cells. A model, combining trapping/detrapping, recombination mechanisms, and electron–phonon scattering, is formulated evidencing how the presence of shallow and deeper band tail states influences the solar cell recombination losses. At low temperatures, the observed cascade capture process indicates that the trapping of the charge carriers by shallow defects is phonon assisted directly followed by their recombination. By increasing the temperature, a phase modification of the CH₃NH₃PbI₃ absorber layer occurs and for temperatures above the phase transition at about 160 K the capture of the charge carrier takes place in two steps. The electron is first captured by a shallow defect and then it can be either emitted or thermalize down to a deeper band tail state and recombines subsequently. This result reveals that in perovskite solar cells the recombination kinetics is strongly influenced by the electron–phonon interactions. A clear correlation between the morphological structure of the perovskite grains, the energy disorder of the defect states, and the device performance is demonstrated.

Highly efficient perovskite based solar cells have the potential to be a game-changing solar array technology for space applications that can be flexible, truly roll-able, ultra-lightweight and highly stowable. Outside earth's magnetic field, however, ionizing radiation causes localized defect states that accumulate and ultimately cause the failure of electronic devices. This study, assesses the radiation hardness of the widely used triple cation based perovskite absorber material, namely Cs_0.05MA_0.17FA_0.83Pb(I_0.83Br_0.17)₃ employing 20 and 68 MeV proton irradiation. Therefore, in situ measurements of the degradation of the proton induced current as well as the photovoltaic performance during proton irradiation are used as two independent metrics. Both measurements suggest that triple cation perovskites even exceed the radiation hardness of SiC, which is a material often proposed to possess an excellent radiation hardness. Our optimized Cs_0.05MA_0.17FA_0.83Pb(I_0.83Br_0.17)₃ based space solar cells reach efficiencies of 18.8% under AM0 illumination and maintain 95% of their initial efficiency even after irradiation with protons at an energy 68 MeV and a total dose of 10¹² p per cm². Degradation under 20 MeV proton irradiation is even lower. Despite the negligible impact on solar cell device performance, this study identifies that proton irradiation is changing the recombination kinetics under low excitation densities profoundly. Dark capacitance–voltage and current–voltage characteristics, photoluminescence spectra as well as photoluminescence and V_oc decays are analyzed in depth. Surprisingly, two fold prolonged PL and V_oc decay times are observed after proton irradiation. Often, such prolongations are attributed to a reduced charge recombination. Our kinetic model, precisely describing the observed time evolution after photoexcitation, however, establishes the prolonged release of trapped minority charge carriers from proton-radiation induced trap states.

An epoxy/carbon nanotubes (CNTs) composite material with a low concentration of multiwalled CNTs (0.5 wt%) has been shown to be applicable in a wide temperature range (up to 160°C) as heating and temperature-sensing element. It can be prepared in any type of geometry allowing a simple application to all kinds of surfaces that have to be sensed and heated. The composite material itself and the electric contacts have demonstrated excellent stability even under extreme ambient conditions. The electrical resistivity of the composite has shown a temperature dependence consistent with the fluctuation-induced tunneling model. This model assumes that the electrical resistance of the nanotube network is dominated by the interconnections between the individual nanotubes rather than by the nanotube resistance itself.

A detailed electric noise investigation of polymer:fullerene solar cells, at 300 K under dark conditions, is reported. The experimental noise results are interpreted in terms of a model taking into account the device capacitance and recombination resistance. Relevant parameters of the solar cells can be computed through fluctuation spectroscopy, and the results have been compared with those obtained by alternative techniques. After a thermal treatment at 340 K, a modification of the voltage-spectral traces has been observed and related to a strong cell resistance reduction.