An organic photosensitive optoelectronic device comprising: two electrodes (110, 140) in superposed relation comprising an anode and a cathode; a photoactive region comprising at least one donor material and at least one acceptor material disposed between the two electrodes to form a donor-acceptor heterojunction, wherein the at least one donor material has a Lowest Unoccupied Molecular Orbital energy level (LUMO don) and a Highest Occupied Molecular Orbital energy level (HOMO don); and an exciton-blocking hole filter disposed between the anode and the at least one donor material, wherein the hole filter comprises a mixture comprising at least one anode-side wide energy gap material and at least one hole conducting material, and wherein the at least one anode-side wide energy gap material has: - a Highest Occupied Molecular Orbital energy level (HOMO AS-WG) energy level larger than or equal to the HOMO don; - a Lowest Unoccupied Molecular Orbital energy level (LUMO AS-WG) smaller than, equal to, or within 0.3 eV larger than the LUMO don; and - a HOMO AS-WG -LUMO AS-WG energy gap wider than a HOMO Don -LUMO Don energy gap; and wherein the at least one hole conducting material has a Highest Occupied Molecular Orbital energy level (HOMO HC) smaller than, equal to, or within 0.2 eV larger than the HOMO don; wherein a first HOMO or LUMO energy level is "smaller than" a second HOMO or LUMO energy level if the first HOMO or LUMO energy level is closer to the vacuum level than the second HOMO or LUMO energy level, a first HOMO or LUMO energy level is "larger than" a second HOMO or LUMO energy level if the first HOMO or LUMO energy level is further from the vacuum level than the second HOMO or LUMO energy level, and two orbital energy levels are "equal to" one another if their energies match to the tenth decimal place; and wherein the mixture comprises the at least one anode-side wide energy gap material and the at least one hole conducting material at a ratio ranging from 10:1 to 1:10 by volume; and wherein the HOMO AS-WG is at least 0.5 eV larger than the HOMO HC. two electrodes (110, 140) in superposed relation comprising an anode and a cathode; a photoactive region comprising at least one donor material and at least one acceptor material disposed between the two electrodes to form a donor-acceptor heterojunction, wherein the at least one donor material has a Lowest Unoccupied Molecular Orbital energy level (LUMO don) and a Highest Occupied Molecular Orbital energy level (HOMO don); and an exciton-blocking hole filter disposed between the anode and the at least one donor material, wherein the hole filter comprises a mixture comprising at least one anode-side wide energy gap material and at least one hole conducting material, and wherein the at least one anode-side wide energy gap material has: - a Highest Occupied Molecular Orbital energy level (HOMO AS-WG) energy level larger than or equal to the HOMO don; - a Lowest Unoccupied Molecular Orbital energy level (LUMO AS-WG) smaller than, equal to, or within 0.3 eV larger than the LUMO don; and - a HOMO AS-WG -LUMO AS-WG energy gap wider than a HOMO Don -LUMO Don energy gap; - a Highest Occupied Molecular Orbital energy level (HOMO AS-WG) energy level larger than or equal to the HOMO don; - a Lowest Unoccupied Molecular Orbital energy level (LUMO AS-WG) smaller than, equal to, or within 0.3 eV larger than the LUMO don; and - a HOMO AS-WG -LUMO AS-WG energy gap wider than a HOMO Don -LUMO Don energy gap; and wherein the at least one hole conducting material has a Highest Occupied Molecular Orbital energy level (HOMO HC) smaller than, equal to, or within 0.2 eV larger than the HOMO don;