In the present work we reveal the existence of the hot carrier photovoltage induced across a p–n junction in addition to the classical carrier generation-induced and thermalization-caused photovoltages. On the basis of the solution of the differential equation of the first-order linear time-invariant system, we propose a model enabling to disclose the pure value of each photovoltage component. The hot carrier photovoltage is fast since it is determined by the free carrier energy relaxation time (which is of the order of 10⁻¹² s), while the thermal one, being conditioned by the junction temperature change, is relatively slow; and both of them have a sign opposite to that of the electron-hole pair generation-induced component. Simultaneous coexistence of the components is evidenced experimentally in GaAs p–n junction exposed to pulsed 1.06 μm laser light. The work is remarkable in two ways: first, it shows that creation of conditions unfavorable for the rise of hot carrier photovoltage might improve the efficiency of a single junction solar cell, and second, it should inspire the photovoltaic society to revise the Shockley–Queisser limit by taking into account the damaging impact of the hot carrier photovoltage.

The photocurrent across crystalline GaAs p-n junction induced by Nd:YAG laser radiation was investigated experimentally. It is established that the displacement current is dominant at reverse and low forward bias voltages in the case of pulsed excitation. This indicates that hot carriers do not have enough energy to overcome the p-n junction until the forward bias significantly reduces the potential barrier. At a sufficiently high forward bias, the photocurrent is determined by the diffusion of hot carriers across the p-n junction. The current–voltage (I-V) characteristics measured at different crystal lattice temperatures show that the heating of carriers by laser radiation increases with a drop in crystal lattice temperature. This study proposes a novel model for evaluating carrier temperature based on the temperature coefficient of the I-V characteristic. It is demonstrated that the heating of carriers by light diminishes the conversion efficiency of a solar cell, not only through thermalisation but also because of the conflicting interactions between the hot carrier and conventional photocurrents, which exhibit opposite polarities. These findings contribute to an understanding of hot carrier phenomena in photovoltaic devices and may prompt a revision of the intrinsic losses in solar cells.

Energy is the binding constraint on unmanned aerial vehicle survey missions, yet most coverage path planners commit to a single sweep pattern regardless of region shape. Our central contribution is to select decomposition granularity and the per-cell coverage pattern by a single physics-based energy criterion. A boustrophedon cellular decomposition with a controlled-concavity merge sets granularity; for each sub-polygon, the planner evaluates a minimum-width lawnmower and a shape-mimicking spiral and keeps the cheaper, with the undecomposed single-sweep solution always in the search space. On 50 benchmark polygons, at a 90% coverage floor, the hybrid reduces energy over a spiral baseline by a median 4.8% (ratio of means 11%) and is never dearer than either fixed pattern at floors of 90–99%. Which pattern is cheaper depends on geometry—lawnmower and spiral are not separable in aggregate (Wilcoxon $p=0.47$). A boundary-reflective zigzag for double coverage achieves 46% fewer turns and 18% less energy than boustrophedon $2\times$. The hybrid keeps the lowest mean energy under ±20% parameter perturbation and on larger fields with wider row spacing.