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In this work, the (Ag,Cu)2ZnSnS4 (ACZTS) thin films were fabricated via sputtering with a multi-target to form different layer stacks, i.e., (S1) ZnS/Sn/Cu/Ag/Mo,(S2) ZnS/Sn/Ag/Cu/Mo and (S3) ZnS/Ag/Sn/Cu/Mo. The stacked precursors were sulfurized through a soft annealing, followed by a two-step sulfurization in a chamber filled with N2 at standard atmospheric pressure. The x-ray photoelectron spectroscopy elemental profile showed a vertical non-uniform distribution of Ag in the film. Based on the results of scanning electron microscopy and electron probe microanalysis, Ag enrichment of the upper surface was beneficial for the grain size. Moreover, a dense, uniform surface could be obtained and the stability of the elemental composition could be maintained. After optimizing the order of the Ag layers, the efficiency of the solar cells increased from 1.30% to 3.65%, an improvement of 181%. The open circuit voltage is increased from 448 mV to 630 mV because of the reduced voids, increased grain size, and reduced CuZn antisite defects.

A 25 nm thick Ag thin film was sputtered between the Cu2ZnSnS4 (CZTS) absorber and Mo electrode to improve the back contact in CZTS solar cells. The CZTS absorber was fabricated via a cost-effective N,N-dimethylformamide-based solution method. X-ray diffraction and Raman spectroscopy demonstrated that Ag diffused into the CZTS and partially substituted Cu, which resulted in an increased lattice constant a and grain size. Ag doping of CZTS (ACZTS) reduced both the Sn-loss and the presence of voids. An ACZTS photovoltaic device (ITO/i-ZnO/CdS/ACZTS/Mo) was fabricated and showed higher EQE than the CZTS device over the wavelength range of 450–800 nm. The open circuit voltage increased (Voc) from 543 to 631 mV, the short circuit current density (Jsc) increased from 10.36 to 14.37 mA, and the efficiency increased from 2.02 to 3.43% after sputtering the Ag layer. This is mainly because Ag functions as a temporary protective layer that made a tighter combination between Mo and the CZTS absorber.

ZAO (ZnO: Al)/Al and ITO/Ag complex back-reflectors were successfully applied to substrate nip and superstrate pin amorphous silicon solar cells respectively. As a result, the short circuit current (Isc) for a cell with a complex back-reflector increases significantly as compared with a cell without a complex back-reflector. For a superstrate pin cell prepared on SnO2 coated glass, the short-circuit current even increases up to 30%.

In this paper we reported the electrical and spectral properties of 1 MeV electron and 3 MeV proton irradiated In0.53Ga0.47As single junction solar cell, which is used as the fourth subcell of wafer bonded GaInP/GaAs//InGaAsP/InGaAs four-junction full spectra solar cell. The equivalent displacement damage dose model was applied to study the radiation effects of solar cell. The results show that the electrical parameters of the solar cell degrade seriously with the increase of irradiation fluences, the reduction of minority carrier life-time and changes of series and shunt resistance caused by irradiation-induced displacement damage are the main reason for the degradation of cell performance. Degradation of spectral response mainly occurred in the long wavelength region of solar cell due to the bigger displacement damage in the base layer of solar cell. Degradation properties of solar cell by electron and proton irradiation can be predicted by electron to proton damage equivalency factor Rep.

The changes in output parameters of 1 MeV electron irradiated MOCVD grown upright metamorphic (UMM) GaInP/GaInAs/Ge triple junction solar cells have been studied. Non-ionizing energy loss (NIEL) approach and MULASSIS simulation were applied for analyzing the effects of irradiation induced displacement damage on cell performance. The influence of base thickness on radiation resistance has been studied by changing the base thickness of top GaInP and middle GaInAs subcell, respectively. The experimental results show that the electrical parameters, Voc, Isc, and Pmax of UMM cell degrade with the increase of electron fluence. The change of spectra response indicates middle GaInAs subcell degrades more severe than top GaInP subcells, and the base thickness of two subcells has different effects on spectra response of UMM cell.

Although conventional III-V compound semiconductors are often considered not to exhibit an efficiency droop, a pronounced low temperature droop was recently measured in AlGaInP/GaAs multi-quantum well structures. In this work, we investigate the efficiency droop in simple optically pumped lattice matched InGaAs/InP single well heterostructures to exclude charge transport related effects from the measurements. The results show that droop is present in this very simplistic setup and, furthermore, starts approximately at the same carrier density as in typical III-N structures. Our results suggest that in its most fundamental form, droop can be explained by Auger-like processes.

Demonstrating and harnessing electroluminescent cooling at technologically viable cooling powers requires the ability to routinely fabricate large area high quality light-emitting diodes (LEDs). Detailed information on the performance and yield of relevant large area devices is not available, however. Here, we report extensive information on the yield and related large area scaling of InP/InGaAs LEDs and discuss the origin of the failure mechanisms based on lock-in thermographic imaging. The studied LEDs were fabricated as mesa structures of various sizes on epistructures grown at five different facilities specialized in the growth of III-V compound semiconductors. While the smaller mesas generally showed relatively good electrical characteristics and low leakage current densities, some of them also exhibited unusually large leakage current densities. The provided information is critical for the development and design of the optical cooling technologies relying on large area devices.

The optical properties of the in situ epitaxial GaN and InP passivated InGaAs∕GaAs near-surface quantum wells, which were fabricated by metal organic vapor phase epitaxy, are investigated. Low-temperature photoluminescence (PL), time-resolved photoluminescence, and photoreflectance are used to study the passivation effect. Both GaN and InP passivations are observed to significantly enhance the PL intensity and carrier lifetime and to reduce the surface electrical fields. Comparison of the methods shows that the epitaxial InP passivation is more effective. However, epitaxial GaN and nitridation methods are comparable with InP passivation.