Patent ID: 8536444

Claim:
A solar cell comprising: a core solar cell having first and second contacts; a bias circuit coupled to the core solar cell, the bias circuit being adapted to provide a time varying bias across the core solar cell, and coupling electrical energy received from the output of the core solar cell to an output load; the time varying bias across the core solar cell alternating between minimum and maximum bias values; the period of alternation of the bias between the minimum and maximum bias values being shorter than the hot carrier cooling time for the core solar cell to extract from the core solar cell, during the time varying bias, photo-excited carriers across a range of energy levels; wherein the bias circuit is adapted to cause a bias value between the first and second contacts to periodically alternate between minimum and maximum bias values, wherein the minimum bias value is a value at which the core solar cell internal built-in electric field is sufficiently high to cause transport of photo-excited carriers within the core solar cell toward the first and second contacts, the maximum bias value being substantially equal to the maximum value of the electrochemical potential of the hot carriers generated within the core solar cell; wherein the bias circuit is adapted to cause the maximum and minimum bias values to be both within the forward bias range of the core solar cell, and the period of the alternation of the bias value to include at least one shorter time interval during which the core solar cell bias instantaneously reaches a reverse bias value, the reverse bias value, duration and period of repetition sustaining an average carrier transport velocity that is sufficient to transport substantially all of the photo-excited carriers within the core solar cell to the first and second contacts within the hot carrier cooling time, and wherein the bias circuit is adapted to provide the maximum and minimum values of the core solar cell bias both within the forward bias range of the core solar cell, and wherein the core solar cell further comprises optical confinement structures in the form of micro cavities having reflective sidewalls on sides of the micro cavities and insulated from the micro cavities by an insulation layer on the sidewalls, a reflective bottom and textured top; an electrical contact mesh on the textured top of the micro cavities; and a contact pad at the reflective bottom of the micro cavities, the electrical contact mesh being electrically connected to the contact pad through the reflective sidewalls; the reflective sidewalls of the optical confinement micro cavities interconnecting the electrical contact mesh on the top of the micro cavities to the contact pad at the bottom of the micro cavities.