NOVELTY - A hyperbranched semiconductor nanocrystal particle comprises a first arm (16), which comprises an intermediate portion (16c) and opposing terminal portions (16a, 16b); and a second arm (20) extending from the intermediate portion of the first arm.    USE - Hyperbranched semiconductor nanocrystal particle for use in a photoactive layer of photovoltaic device (claimed), i.e. hybrid solar cell or hyperbranched nanocrystal-polymer solar cell.    ADVANTAGE - Efficient hybrid solar cell whose blend morphology is controlled by the 3-dimensional (D) structure of a hyperbranched nanocrystal phase is achieved. The cells combine the simple processing and easy fabrication of nanocrystal blend cells with the ordered morphology and transport network of template-based systems. The branching structure of the nanocrystals controls the dispersion of the inorganic phase in the polymer matrix, thus ensuring a large, distributed surface area for charge separation. Defects such as islands and aggregates, which are detrimental to the performance of conventional hybrid cells, are eliminated in hyperbranched particle composites, where blend morphology is dictated entirely by the 3-D structure of the hyperbranched nanocrystal. Hyperbranched particles span the entire device thickness and thus contain a built-in percolation pathway for hopping-free transport of electrons to the anode, thus enhancing electron transport and eliminating the need for strict control of particle dispersion within the matrix. With decreased sensitivity to variations in processing, a simple monolayer of such nanocrystals in a polymer matrix provides a controlled, ordered, and well-defined bulk heterojunction with the dispersion and percolation required for charge separation and transport. A well-defined, closed-packed monolayer of hyperbranched nanocrystals yields excellent performance. The optimization of hyperbranched particle cells is simple, well defined, clearly distinguished, and easily attained.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for:    (1) a method of preparing a hyperbranched semiconductor nanocrystal particle comprising contacting a first semiconductor precursor, a second semiconductor precursor, and a surfactant mixture comprising a bifunctional surfactant; and    (2) a photovoltaic device comprising a cathode; an anode; and a photoactive layer comprising a monolayer of hyperbranched semiconductor nanocrystal particles, where the photoactive layer is disposed between the cathode and the anode.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view illustrating the hyperbranched particle.    Core (14)    First arm (16)    Opposing terminal portions (16a, 16b)    Intermediate portion (16c)    Second arm (20)