Large-Grain Spanning Monolayer Cu ZnSnSe Thin-Film Solar Cells Grown from Metal Precursor.

The persistent double layer structure whereby two layers with different properties form at the front and rear of absorbers is a critical challenge in the field of kesterite thin-film solar cells, which imposes additional nonradiative recombination in the quasi-neutral region and potential limitation to the transport of hole carriers. Herein, an effective model for growing monolayer CZTSe thin-films based on metal precursors with large grains spanning the whole film is developed. Voids and fine grain layer are avoided successfully by suppressing the formation of a Sn-rich liquid metal phase near Mo back contact during alloying, while grain coarsening is greatly promoted by enhancing mass transfer during grain growth.

"Designing high-performance nighttime thermoradiative systems for harvesting energy from outer space" by Zhang et al.: comment.

The current-voltage characteristics presented by Zhang et al. in their recent work on designing thermoradiative systems overestimate the achievable power using the proposed material by several orders of magnitude.

Assessing the Nature of the Distribution of Localised States in Bulk GaAsBi.

A comprehensive assessment of the nature of the distribution of sub band-gap energy states in bulk GaAsBi is presented using power and temperature dependent photoluminescence spectroscopy. The observation of a characteristic red-blue-red shift in the peak luminescence energy indicates the presence of short-range alloy disorder in the material. A decrease in the carrier localisation energy demonstrates the strong excitation power dependence of localised state behaviour and is attributed to the filling of energy states furthest from the valence band edge.

Competition between the charge transfer state and the singlet states of donor or acceptor limiting the efficiency in polymer:fullerene solar cells.

We study the appearance and energy of the charge transfer (CT) state using measurements of electroluminescence (EL) and photoluminescence (PL) in blend films of high-performance polymers with fullerene acceptors. EL spectroscopy provides a direct probe of the energy of the interfacial states without the need to rely on the LUMO and HOMO energies as estimated in pristine materials. For each polymer, we use different fullerenes with varying LUMO levels as electron acceptors, in order to vary the energy of the CT state relative to the blend with [6,6]-phenyl C61-butyric acid methyl ester (PCBM).

Secondary electron emission contrast of quantum wells in GaAs p-i-n junctions.

The secondary electron (SE) signal over a cleaved surface of GaAs p-i-n solar cells containing stacks of quantum wells (QWs) is analyzed by high-resolution scanning electron microscopy. The InGaAs QWs appear darker than the GaAsP barriers, which is attributed to the differences in electron affinity. This method is shown to be a powerful tool for profiling the conduction band minimum across junctions and interfaces with nanometer resolution.