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Abstract-The energy spectrum of the confined states of a quantum dot intermediate band (IB) solar cell is calculated with a simplified model. Two peaks are usually visible at the lowest energy side of the subbandgap quantum-efficiency spectrum in these solar cells. They can be attributed to photon absorption between welldefined states. As a consequence, the horizontal size of the quantum dots can be determined, and the conduction (valence) band offset is also determined if the valence (conduction) offset is known.Index Termsquantum dots.-Energy states, optical pumping, photovoltaic cells,

Abstract-A procedure for measuring the overheating temperature (AT) of a p-n junction area in the structure of photovoltaic (PV) cells converting laser or solar radiations relative to the ambient temperature has been proposed for the conditions of connecting to an electric load. The basis of the procedure is the measurement of the open-circuit voltage (Voc ) during the initial time period after the fast disconnection of the external resistive load. The simultaneous temperature control on an external heated part of a PV module gives the means for determining the value of Vb c at ambient temperature. Comparing it with that measured after switching OFF the load makes the calculation of AT possible. Calibration data on the Voc = f(T) dependences for single-junction AlGaAs/GaAs and triple-junction InGaP/GaAs/Ge PV cells are presented. The temperature dynamics in the PV cells has been determined under flash illumination and during fast commutation of the load. Temperature measurements were taken in two cases: converting continuous laser power by single-junction cells and converting solar power by triple-junction cells operating in the concentrator modules.

The calculation of the energy spectrum and absorption coefficients of quantum dot nanostructured intermediate band solar cells using the Empiric K • P Hamiltonian method and its agreement with experimental data are summarized. The well established Luttinger Kohn Hamiltonian modified by Pikus and Bir for strained material, such as quantum dot arrays, is presented using a simplified strain field that allows for square band offsets. The energy spectrum and absorption coefficients are calculated with this new Hamiltonian. With the approximations made the energy spectrum results to be exactly the same but the absorption coefficient fits experiments less accurately. The computer time using the latter Hamiltonian is much longer than the former one.

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